JPH02269573A - Honing stick - Google Patents

Abstract

PURPOSE:To finish the whole surface of a subject to be processed at high quality by forming at both ends of a honing stick in its axial direction cutting faces which make contact with the surface of the subject to be processed, and forming in the intermediate portion between the cutting faces in their cross direction a recessed portion which does not make contact with the surface of the subject to be processed. CONSTITUTION:The surface of a subject to be processed is honed by cutting faces 17a,17b provided at both ends of a honing stick 17 in its axial direction. A recessed portion 28 formed in the intermediate portion between the cutting faces 27a and 27b in their cross direction cancels out excessive grinding of that portion which may be caused by reciprocating movement of the honing stick 17. As a result, generation of failures in processing such as narrowing of the diameter at both ends is avoided, and the whole surface of the subject to be processed is honing-finished at high quality.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvement of a honing stone used in honing.

(Prior Art) For example, in order to reduce the weight of the engine and improve thermal conductivity, automobile engine cylinders have conventionally been manufactured by forming a cylinder block from an aluminum alloy and fitting a cast iron cylinder liner into the cylinder block. It was configured. However, when fitting the cylinder liner,
Problems have arisen in that the adhesion between the two may not be good or deformation may occur.

Therefore, in recent years, in order to further reduce the weight of the engine and improve thermal conductivity, the cylinder itself has been manufactured from an aluminum alloy without using the cylinder liner.

Hypereutectic At-8i alloy, which has a silicon content of about 16 to 18% by weight, is known as an aluminum alloy used in this type of cylinder. The silicone particles improve wear resistance, and the recesses between the raised silicone particles ensure that lubricating oil is retained.

The inner wall surface processing of these workpieces such as cylinders is
As is well known, this is done by honing, and the
As shown in the figure, a honing device having a honing head 5 is used.

Inside the body 6 of the honing head 5, a bushing rod 7 on which a tapered cone 8 is formed is provided so as to be movable in the ll11 direction. Further, 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 taper cone 8.

Therefore, when the bushing rod 7 is pushed down by means such as hydraulic pressure (not shown), the stone holder 9 is moved outward by the taper cone 8, whereby the grinding wheel 10 is pressurized and expanded against the inner wall surface 4 of the workpiece 1. It is now possible to do so. Further, a drive motor (not shown) and a hydraulic device that performs reciprocating motion are connected to the body 6, so that the honing head 5 can freely rotate and reciprocate.

Then, by applying expansion pressure to the grindstone 10 and reciprocating in the axial direction while rotating the honing head 5,
The inner wall surface 4 of the workpiece 1 is to be processed.

As shown in FIG.
A slit 27 is formed in the 10a, and the slit 27 is used to remove chips and improve processing efficiency.

Further, the reciprocating stroke of the grindstone 10 is determined so that the grindstone 10 slightly protrudes at the upper and lower ends of the cylinder 1, as shown in FIG. 1-0. This amount of protrusion, or overstroke a, is empirically determined to be approximately 1/4 of the length of the grinding wheel 10.
It is taken in the range of 1-/3 from .

(Problem to be Solved by the Invention) However, especially when honing a blind hole, it is not possible to overstroke the whetstone 0 at the lower end, so as shown in FIG.
It was not possible to process it without removing it. If this relief b was not taken, there would be a drawback that the inner diameter on the stop side would become small and the hole would become tapered.

In addition, even for cylinders 1 that are open at the upper and lower ends, the inner wall surface 4 is ground extra in the length direction in order to obtain machining accuracy, that is, straightness (for example, 5μ or less) of the inner wall surface 4 on which the piston slides. It was being processed. However, in recent cylinders, there is a strong demand for increasing the rigidity of the wall that supports the crankshaft, so the opacity and cone a have been reduced.
There is a design constraint to reduce the extra grinding process as much as possible.

However, when the overstroke a is reduced, processing defects as shown in FIG. 12 occur on the inner wall surface 4 of the cylinder 1. In other words, Figure (A) shows a cylinder in which the bore diameter at the lower end is small and the cross section is tapered, and Figure (B) shows that the middle part of the inner wall surface 4 is ground more excessively than other parts. It shows a cylinder with a cylindrical cross-section. Therefore, if the overstroke a is reduced, the cylindricity deteriorates, and as a result, the roundness and straightness reach the permissible limits for the product, which results in the problem of not being able to manufacture high-quality products. there were.

The present invention has been made in view of the problems of the prior art, and is directed to honing pressurization of blind holes, or
An object of the present invention is to provide a honing stone that can be honed with high quality without causing processing defects even in honing processing with a reduced overstroke a.

(Means for Solving the Problems) The present invention for achieving the object described in -1- has a plurality of bar-shaped honing wheels, and rotates each honing wheel while expanding it toward the surface side of the workpiece. In a honing device that processes the surface by reciprocating motion and an axial direction, a cutting surface that contacts the surface of the workpiece is formed at both ends in the axial direction of each of the honing wheels. At the same time, this honing stone has a recess formed in the middle part of these cutting surfaces that does not contact the surfaces.

(Function) If the honing stone is configured in this way, the surface of the workpiece will be processed by the cutting surfaces at both ends in the axial direction, and the reciprocating movement of the honing stone will machine this part due to the recess formed in the middle part. Grinding will not proceed excessively. As a result, the surface of the workpiece can be machined without causing machining defects such as a decrease in the diameter of both ends.

(Example) Hereinafter, one example of the honing stone according to the present invention will be described based on the drawings.

FIG. 1 is a perspective view showing one embodiment of the honing wheel according to the present invention, FIG. 2 is a graph showing the relationship between the ratio of the recessed portion to the total length of the grinding wheel and straightness, and FIG. 3 is a graph showing another embodiment of the honing wheel A perspective view showing an example; FIG. 4 is a side view showing still another embodiment;
Figures 5 and 6 are cross-sectional views showing the honing head used during honing, and Figure 7 is a view showing how the grindstone is installed, which is common to the parts shown in Figures 8 and 9. Part H
, the same reference numerals will be used, and some explanations will be omitted.

First, the configuration of the honing head 5 incorporated into the honing machine will be explained based on FIGS. 5 to 7.

The illustrated honing head 5 performs multi-stage honing on the inner wall surface 4 of the cylinder 1 as a workpiece, and includes a coarse grindstone 17 for semi-honing and a finishing grindstone for finish honing. 18, and semi-finish honing is performed by selectively pressurizing and expanding both of these grindstones 17 and 18.

Hollow top joints l-], ], and bolts 12 are fixed to the upper part of the main body 6.

An axially movable bushing rod 13 is attached to the through hole of the top joint 11, and a processing 1 push rod 14 is provided inside the coarse bushing rod 13 so as to be axially movable. ing. A coarse taper cone 15 having a tapered surface 15a is connected to the end of the coarse bush rod 13.
Similarly, the tapered surface 16a is also attached to the mm bushing rod 14.
A finishing tapered cone 16 is attached.

As shown in FIG. 7, on the outer periphery of the board 6, there is a coarse stone boulder 19 holding a bar-shaped coarse grindstone 17, the tapered surface 19a of which is connected to the coarse taper cone.
It is attached in a state where it is in contact with the tapered surface 15a of No.5. On the other hand, the finishing stone holder 20 holding the finishing whetstone 18 is also mounted with its tapered surface 20a in contact with the tapered surface 16a of the finishing taper cone 16. Both of these stone holders 1-9.20
As shown in Fig. 6, there are 6 concentric circles at equal intervals
pcs installed.

In addition, in order to tighten the coarse grinding wheels 1 and 7 in the axial direction of the body 6, a spring 21 that applies an elastic force in the direction of pulling up the coarse tapered cone 15 in the -1 direction in the figure is used.
- It is installed between the joint joint 21 and the coarse taper cone 15. Further, in order to move the coarse phase stone halter 19 as the coarse phase taper cone 15 is pulled up, a holder 1 is attached to the coarse phase taper cone 15.
A return pin 23 inserted into the hole 25 of 9 is fixed.

Similarly, in order to tighten the finishing whetstone 18 in the axial direction of the body 6, a spring 22 that applies an elastic force in the direction of pressing the finishing taper cone 16, or a spring 22 that applies a force to the body 6 It is installed between. Further, a return pin 24 which is pressed into the hole 26 of the boulder 20 is fixed to the finishing taper cone 16.

A pressure device (not shown) is connected to both bush rods 13, 14 to selectively press down each rod 13, ]4 using hydraulic pressure or the like. Further, a drive motor for rotational motion and a hydraulic device for reciprocating motion are connected to the body 6, so that the honing head 5 can freely rotate and reciprocate.

As shown in FIG. 1, the coarse grindstone 17 has cutting curves 17a at both ends in the axial direction that contact the inner wall surface 4 of the cylinder 1.
, 17b are formed. In addition, these double cut surfaces 1.
Between 7 a and 17 b, that is, approximately at the center of the grindstone 17 in the length direction, a recess 28 is formed at a predetermined depth and does not contact the inner wall surface 4 . The length of this recess 28 is
As shown in the figure, it is "1". In addition, both cut surfaces 17a
, 17b are formed to have the same length in order to improve the balance between the two lower parts of the grinding wheel 17, and their length is r (
L-1)/2J. For example, the length of the whetstone 17 is only 7
If it is 0 mm, the length 1 of the recess 28 is preferably 30 mm, and the lengths of both cut surfaces 17a and 17b are each 20 m.
m. Although not shown, the finishing whetstone 18 is also formed in the same manner.

Next, the operation of this embodiment will be explained.

When the coarse phase punch rod 13 is pushed down by a pressurizing device (not shown), the coarse phase taper cone 15 is also pushed down. As the coarse taper cone 15 moves downward, both the upper and lower tapered surfaces 1.5a abut against the upper and lower tapered surfaces 19a of the rough stone holder 19 while moving the holder 19 outward. It will move evenly. Therefore, the coarse grindstone 17 protrudes outward and comes into pressure contact with the inner wall surface 4 of the cylinder 1. Furthermore, by controlling the amount of depression of the rough-angle bushing rod 13, the pressing force of the rough-shape grindstone 17, that is, the expansion pressure, can be controlled, so that the inner wall surface 4 of the cylinder 1 can be Semi-honing processing will be performed.

In grinding the cylinder 1 with this coarse grindstone 17, the effect when honing is performed by reducing the above-mentioned overstroke a will be explained.

In the honing stone 17 of this embodiment, the cutting surfaces 17a and 17b at both ends in the axial direction perform the grinding, while the recess 28 formed approximately at the center in the length direction of the honing stone 17 is formed on the inner wall surface 4. Since there is no contact, there is no equivalent contribution to grinding. In this way, during the reciprocating motion of the grinding wheel 7, the central portion that can come into most contact with the inner wall surface 4 of the cylinder 1 is the concave portion 28, so that grinding in this central portion does not proceed excessively. Even if the overstroke a is reduced, the diameters of both ends do not become smaller, and a high-quality inner wall surface 4 with good straightness can be provided.

Similarly, by controlling the amount by which the finishing bushing rod 14 is pushed down, the expansion pressure of the finishing grindstone 18 can be controlled, and under the desired expansion pressure, the Finish honing will be performed. It goes without saying that even in the honing process using this finishing whetstone 18, a high quality inner wall surface 4 with good straightness can be processed.

Next, the relationship between the ratio of length 1 of the recess 28 to the total length of the grindstone 17 and product accuracy will be explained based on test results.

For product accuracy, we use the straightness of the inner wall of the cylinder.
The test results are shown in Figure 2. The permissible straightness for cylinder products is 5 lt or less. Further, the recessed portion 28 of the grindstone 17 is formed so that both the upper and lower cutting surfaces 17a and 17b have the same length.

As is clear from the figure, the length 1 of the recess 28 is
7]/2, the straightness is the best, and after this value, the straightness tends to gradually deteriorate regardless of whether the length of the recess 28 becomes longer or shorter. however,
It was found that when the length 1 of the recess 28 is 0°2L or more and 0.8L or less, the straightness is below the allowable value, and the machined cylinder 1 is suitable for use as a product.

If the length 1 of the recess 28 is greater than 0.8L, the ratio of the cutting surfaces 17a and 17b to the total length of the grinding wheel 17 will be too small, which will rapidly increase the wear of the grinding wheel 17 and reduce machining efficiency. .

For this reason, the effect of improving the straightness was not achieved, the straightness fell below the allowable value, and it was found that the machined cylinder 1 was not suitable for use as a product.

Furthermore, if the recess 28 is too long, when the grindstone 17 reciprocates in the axial direction, the cutting surface 17a on the second part side cannot maintain contact with the inner wall surface 4 of the cylinder 1, and the recess 28 It may come out from the edge. At this time, the balance of the grindstone 17 becomes poor, and the recess 28 collides with the inner wall surface 4.
This is not preferable because it may cause processing defects such as scratches.

On the other hand, if the length l of the recess 28 is smaller than 0.2L, the ratio of the recess 28 to the total length of the grinding wheel 1-7 becomes too small. I couldn't get it out.

In the above-described embodiment, the grinding wheel 17 has a concave portion 28 approximately in the center thereof.
However, the present invention is not limited to this grindstone shape. For example, as shown in FIG. The recess 28 may be formed in the recess 28 .

Furthermore, as shown in FIG. 4, the upper and lower cutting surfaces] 7a, 1
At least one of 7b may have a tapered cross section. For example, the total length of the grindstone 17 is 70 mm,
Length 1 of recess 28 is 30 mm, both incision surfaces 17a, 17b
When the length of each is 20 mm, the amount of protrusion of the taper is preferably about 50 to 100 μ at the end.

(Effects of the Invention) As described above, the present invention provides cutting surfaces that contact the surface of the workpiece at both ends of each honing stone in the axial direction, and the above-mentioned cutting surfaces in the middle of these cutting surfaces. Since this honing stone has a concave part that does not touch the surface, even when honing a blind hole or honing a honing process that reduces the overstroke amount of the whetstone, there will be no machining defects such as a smaller diameter at both ends. This has a great practical effect in that it is possible to finish the surface of the workpiece with high quality without causing any damage.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of a honing wheel according to the present invention, FIG. 2 is a graph showing the relationship between the ratio of concave portions to the total length of the grinding wheel and straightness, and FIG. 3 is a diagram showing another example of the honing wheel according to the present invention. A perspective view showing an example; FIG. 4 is a side view showing still another embodiment;
Fig. 5 is a sectional view showing the honing head used during honing processing, Fig. 6 is a sectional view taken along the line ■-■ in Fig. 5, and Figs. 8 is a schematic sectional view of the honing head to explain the honing process, and FIG. 9 is a perspective view showing a conventional grindstone. Figure 10.11 is a schematic cross-sectional view of a cylinder used to explain the over rotor in honing processing,
FIGS. 12(A) and 12(B) are cross-sectional views of the cylinder showing defective machining. DESCRIPTION OF SYMBOLS 1... Cylinder (workpiece), 17... Roughing grindstone (grindstone), 17a, 17b - Cutting surface, 18... Finishing grindstone (grindstone), 28... Recessed portion.

Claims (1)

[Claims] In a honing device that has a plurality of bar-shaped honing stones, each honing stone is rotated and reciprocated in the axial direction while expanding toward the surface of a workpiece, thereby processing the surface of the workpiece. , characterized in that cutting surfaces that contact the surface of the workpiece are formed at both ends in the axial direction of each of the honing wheels, and a recess that does not contact the surface is formed in the middle of these cutting surfaces. Honing whetstone.