JPH0760638A - Inside surface grinding method - Google Patents

Abstract

PURPOSE:To improve productivity, accuracy and a maintenance characteristic in work of a fragile material or the like by inserting a work inside of a chucking ring which has an inside diameter of almost the same dimension with an outside diameter of the work and in which a slit is formed in the axis direction, fixing the chucking ring to fixing metal fittings in this condition, and grinding an inside surface of the work. CONSTITUTION:A chucking ring 1 which has an inside diameter of almost the same dimension with an outside diameter of a work 3 and in which a slit 2 is formed in the axis direction, is formed. In a condition where the work 3 is inserted inside of this chucking ring 1, the chucking ring 1 is fixed by fixing metal fittings 4 such as a chuck of an inside surface grinder or the like. Thereby, the chucking ring 1 is reduced in the inside diameter by the slit 2, and grips the work 3, and grinds an inside surface of the work 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner surface grinding method for fixing a work piece inserted in a chucking ring and grinding the inner surface of the work piece.

In the internal grinding process for forming the ring shape, particularly when performing heavy grinding of brittle materials and grinding of low-strength materials such as thin-walled rings, it is possible to hold the workpiece as uniformly as possible from the outer periphery and improve accuracy. Good inner surface grinding is desired.

[0003]

2. Description of the Related Art Conventionally, a work piece in the inner surface grinding machine shown in FIG. 7 uses a fixing metal fitting consisting of a scroll chuck having 3 to 6 claws, for example, a scroll chuck having 3 claws as shown in FIG. 8 or a hydraulic chuck. Then, the inner surface was ground with a grindstone to be machined to a desired size. In addition, a thin sleeve made of rubber or metal is inflated by air pressure or hydraulic pressure to grasp and fix a work piece for processing. A brief description will be given below.

FIG. 7 shows an example of an inner surface grinding machine. Here, the chuck is a fixture for fixing the workpiece with three claws. The grindstone is a grindstone for grinding the inner surface of a workpiece fixed by a chuck.

The headstock holds and rotates a chuck. The wheel head has a mechanism for moving the wheel in the axial direction and rotating the wheel around the axis.

The table is a table on which a grindstone head and a headstock are mounted. The frame is for mounting a table, headstock, grindstone, etc. FIG. 8 schematically shows a state in which the workpiece is fixed to the chuck of the inner surface grinding machine of FIG. 7 and the inner surface is ground with a grindstone. The chuck has three claws, and the work piece is held by the claws. And
The inner surface of the held work is ground with a rotating grindstone.

[0007]

If the workpiece is fixed by the above-mentioned fixing metal fittings and the inner surface is ground, brittle materials such as ceramics, especially impact strength and tensile strength are low. There was a problem that cracks and cracks were very likely to occur due to forces such as fixing / grasping with tools and grinding resistance (see Fig. 8).

Particularly in the case of ring-shaped inner surface grinding as shown in FIG. 8, the gripping force applied to the outer circumference by the chuck is ideally such that hydrostatic pressure acts on the entire outer circumference. However, in reality, the grasping force acts from 3 to 6 directions in a form similar to point contact or line contact, and local deformation and breakage due to bending stress (tensile stress) are likely to occur. This is because it is difficult to hold the entire outer circumference of the workpiece by the jaws of the chuck, and the grasping surface of the jaws and the work surface are not necessarily the same and do not adhere uniformly. In order to avoid this deformation and damage, if the chuck operating force is lowered, the chuck will not operate properly, the surface pressure of the gripping surface, and the contact surface will decrease, resulting in dead length (stopping of the workpiece in the axial direction) and other workpieces. However, there is a problem in that it is impossible to secure a reliable grasp of the workpiece, and the force mainly due to the grinding resistance between the grindstone and the workpiece causes the workpiece to drop or be damaged, the machining accuracy to decrease, and the claw to be damaged.

In order to bring the conventional method of grasping a workpiece with a plurality of claws closer to an ideal state, the workpiece is grasped from multiple directions by increasing the number of claws and the true outer surface of the workpiece is grasped. It is desired to improve the accuracy such as roundness and surface accuracy so that the grasping surfaces of the claws match each other as much as possible, and to improve the operability without lowering the rigidity of the chuck itself.

In order to solve the above problems and the like, a thin sleeve made of rubber or metal is inflated by air pressure or hydraulic pressure to grasp a workpiece, but in both cases, the precision is low and the grasping force is low. There was a problem that it was low and expensive.

The present invention solves these problems.
When forming a ring shape by internal grinding, insert the workpiece into a chucking ring with slits and then fix it. Brittle materials such as ceramics and low strength materials that were difficult with conventional processing methods. The object of the present invention is to realize a method of fixing the inner surface by heavy grinding and processing of low-strength shape in a simple and highly accurate manner in terms of productivity, accuracy, equipment and maintenance.

[0012]

[Means for Solving the Problems] Means for solving the problems will be described with reference to FIG. In FIG. 1, the chucking ring 1 has an inner diameter φD that is substantially the same as the outer diameter φd of the workpiece 3, and has a slit 2 in the axial direction. For example, (φD−φd) is −0. .2 to +0.5 mm.

The work 3 is a work to be ground and has an outer diameter φd. Fixing bracket 4
Is a metal fitting for fixing the chucking ring 1 in which the workpiece 3 is inserted.

[0014]

According to the present invention, as shown in FIG. 1, the chucking ring 1 is fixed inside the chucking ring 1 after the workpiece 3 is inserted into the chucking ring 1. The inner surface of the grasped workpiece 3 is ground.

At this time, the inner diameter φD of the chucking ring 1
And the outer diameter φd of the workpiece 3 (φD−φd) is −0.
It is set to 2 to +0.5 mm. In addition, when the workpiece 3 is long, it is divided into a plurality of chucking rings 1 and they are fixed to each other.

Therefore, when forming a ring shape by the inner surface grinding process, the workpiece 3 is inserted into the chucking ring 1 having the slit 2 and then uniformly tightened and fixed from the entire outer peripheral surface. It becomes possible to easily and accurately fix brittle materials such as ceramics, heavy grinding of low-strength materials, and processing of low-strength shapes, which were difficult with the method, in terms of productivity, accuracy, equipment and maintenance. .

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the construction and operation of an embodiment of the present invention will be described in detail with reference to FIGS.

FIG. 1 (a) shows a block diagram when viewed obliquely. This shows a state in which the workpiece 3 is inserted and fixed to the chucking ring 1 according to the present invention in the fixing metal fitting (chuck) 4 of the inner surface grinding machine as shown in FIG.

In FIG. 1 (a), a chucking ring 1 has an inner diameter φD that is approximately the same as the outer diameter φd of a workpiece 3 and has a slit 2 in the axial direction. φD−φd) has a value of −0.2 to +0.5 mm, and is for fixing to the fixing metal fitting (chuck) 4 of the inner surface grinding machine as shown in the figure.

The slit 2 is a slit provided in the chucking ring 1 in the axial direction thereof.
This is for reducing the size of the chucking ring 1 so that the chucking ring 1 comes into contact with the outer peripheral surface of the workpiece 3 when it is pushed from the outer periphery to the center by the fixing fitting.

The workpiece 3 is a workpiece to be ground internally by an internal grinder, and is, for example, cylindrical sintered ferrite or the like and has an outer diameter φd.
The fixing fitting 4 is a chuck of an inner surface grinding machine or the like, and fixes the chucking ring 1 having the workpiece 3 inserted therein.

Next, according to the order of FIG.
Under the configuration of (a), the procedure for performing the inner surface grinding process will be described in detail. In FIG. 1B, S1
Grinds the outer diameter reference surface. This is because when the accuracy of the outer diameter of the workpiece 3 to be ground is not sufficient, the outer diameter is ground to obtain the reference surface of the outer diameter of the workpiece 3, and the chucking ring 1 is used as much as possible. In addition, pretreatment is performed so that the entire outer circumference can be grasped reliably and with high accuracy.

In step S2, the workpiece 3 is inserted into the chucking ring 1. In this, the workpiece 3 having the outer diameter reference surface in S1 is inserted into the chucking ring 1 provided with the slit 2.

S3 is chucking ring 1 + workpiece 3
Insert it into the center of the fixing bracket (chuck claw) of. As a result, the chucking ring 1 into which the workpiece 3 is inserted is inserted into the center of the fixture (chuck) shown in FIG.

In step S4, the chucking ring 1 and the workpiece 3 are tightened by the chuck. As shown in FIG. 1 (a), this fixes the chucking ring 1 + workpiece 3 inserted in S3 inward by tightening with three claws. At this time, as will be described later, since the chucking ring 1 is gradually tightened from the outside in three directions by a chuck, the chucking ring 1 shrinks in the outer peripheral direction and comes into surface contact with the workpiece 3 and is uniformly tightened (see FIG. 4 and FIG. 5 later).

In step S5, the inner surface of the workpiece 3 is ground. This grinds the inner surface of the workpiece 3 fixed in S4 with a grindstone.
In step S6, the chucking ring 1 and the workpiece 2 are removed from the fixture (chuck).

In step S7, the workpiece 3 is extracted from the chucking ring 1. As described above, after the workpiece 3 is inserted into the chucking ring 1 and inserted into the center of the fixing metal fitting 4 of the inner surface grinding machine to be fixed, and the inner surface is ground,
Remove the chucking ring 1 + workpiece 3 from the fixture 4, and pull out the workpiece 3. With these, the fixing bracket 4
When the work piece 3 is fixed with, the work piece 3 is inserted and fixed inside the chucking ring 1 having the slit 2, so that the work piece 3 can be pressed by the surface evenly from the outer circumference of the work piece 3 to be fixed, and the work piece is fragile. It is possible to fix the workpiece 3 made of material without damaging the workpiece 3 and to grind the inner surface with high accuracy.

FIG. 2 is a diagram for explaining a concrete example of the present invention (No. 1).
Indicates. This is the fixing bracket 4, the chucking ring 1,
And the example of the workpiece 3 is shown. FIG. 2A shows a chuck (three claws). Here, as shown in the figure, in the opened state of the chuck, it has φ28 (diameter represents 28 mm).

FIG. 2B shows an example of the chucking ring 1. Here, the dimensions are as shown in the drawing, corresponding to the dimensions of the workpiece 3 in FIG. Here, the chucking ring 1 is required to have elasticity, flexibility, and hardness to withstand repeated use, and to have uniform thickness so as not to affect the accuracy of the workpiece 3. is there. At the same time, the shape of the chucking ring 1 is set in consideration of the chucking type, the strength of the workpiece 3, and the required processing accuracy. The thicker the chucking ring 1 is, the higher the durability is, and the accuracy of the chucking ring 1 itself is improved, but this hinders uniform grasping. The length may be the same as the workpiece 3. The longer the length, the lower the accuracy of the chucking ring 1 itself. However, when the length-to-diameter ratio of the work piece 3 exceeds 2: 1, the short chucking ring 2 is divided into two or more. The material is HR
A material having a hardness of about C60 is desirable, but there are limitations such as elasticity, flexibility, heat treatment, machining, and manufacturing cost. From these conditions, in mass production, for example, the outer diameter is φ28.
mm, the inner diameter is 25 mm, the length is 30 mm, and the slit 2 has a width of 1 mm. The material used was a tempered steel of about HRC35.

FIG. 2C shows an example of the work piece. Here, it is sintered ferrite, and as shown in the drawing, the inner diameter before processing is φ19.5 to 20.5 mm, and the outer diameter during processing is φ25 mm (outer diameter ground).

Next, the processing procedure when the inner surface is ground under the conditions of FIG. 2 will be described in detail with reference to FIG. Figure 3
FIG. 2 is a diagram (part 2) for explaining a specific example of the present invention.

FIG. 3A shows a fixing metal fitting (chuck) 4
The state where the chucking ring 1 and the workpiece 3 are fixed is shown in FIG. This is the fixture (chuck) of Fig. 2 (a).
The chucking ring 1 in which the workpiece 3 is inserted is inserted into the central portions of the three claws 4 and the three claws are extended toward the center and tightened and fixed.

FIG. 3B shows an axial view of the state of FIG. 3A. Here, the three claws of the fixing metal fitting (chuck) 4 are respectively extended toward the center and uniformly pressed from the outer circumference of the chucking ring 1. As a result, the chucking ring 1 shrinks slightly and the inner workpiece 3
It comes into surface contact with and is uniformly tightened from the outer periphery to be fixed.
When the chucking ring 1 contracts slightly, the contraction is absorbed by the slit 3.

As described above, by inserting the workpiece 3 inside the chucking ring 1 and fixing both of them by the claws of the fixing metal fitting 4 from the outer periphery, the workpiece 3 inside the chucking ring 1 is fixed. Since the chucking ring 1 can be uniformly tightened from the entire surface or many surfaces,
Even with the sintered ferrite workpiece 3 to be ground internally according to the present invention, it was possible to almost completely eliminate the damage rate of 10 to 20% conventionally. At this time, in the structure in which the workpiece 3 is put inside the chucking ring 1 of the present invention,
Even if the tightening force of the fixing metal fitting 4 was reduced to about 80% of that in the conventional case, the fixing could be sufficiently performed.

Next, referring to FIGS. 4 and 5, the workpiece 3
The fitting between the chucking ring 1 and the chucking ring 1 will be described in detail. FIG. 4A shows the outer diameter / inner diameter.

FIG. 4A-1 shows the outer diameter of the workpiece 3. As shown in the figure, the outer diameter of the workpiece 3 is φd. Figure 4
(A-2) indicates the inner diameter of the chucking ring 1.
As shown, the chucking ring 1 has an inner diameter of φD.

FIG. 4B shows an example of fitting of the workpiece 3 and the chucking ring 1. φD <φd is not desirable. (A) If the difference between φD and φd exceeds 0.2, it becomes very difficult to manually insert the workpiece 3 into the chucking ring 1 (the harder the material, the more remarkable).

(B) Since the φD surface and the φd surface strongly rub against each other at the time of insertion, scratches and wear occur. (C) As shown in (a-1) of FIG. 5, when a gap is generated, the grasping force of the nail is concentrated on a part, which has an adverse effect by using the chucking ring 1. Further, the frictional force on the friction surfaces of the claw and the chucking ring 1 and the work 3 has a direction that prevents the chucking ring 1 from closing, and strong friction occurs on each contact surface, causing scratches or dents. Cause damage.

ΦD≈φd is desirable. (A) The force required to bring the φD surface and the φd surface into close contact is minimized.

(B) Almost no deformation occurs when the chucking ring 1 is tightened, and fatigue is unlikely to occur. (C) However, compared to (C), wear is likely to occur when the workpiece 3 is inserted.

It is desirable that φD> φd. (A) Wear is unlikely to occur when the workpiece 3 is inserted into the chucking ring 1.

(B) However, since this is also a matter of degree, φD>
If φd becomes extreme, the chucking ring 1 will be greatly deformed when tightened, and fatigue will easily occur. (C) The width of the slit 2 for allowing deformation during tightening increases, and this interferes with the claw (see (b) of FIG. 5).

(D) Circumferential rubbing occurs between the gripping surface of the claw and the outer peripheral surface of the chucking ring 1 during tightening, and this increases, causing scratches and wear on the mating surface (Fig. 5 (c)).

FIG. 5 is an explanatory view (No. 2) for fitting the workpiece and the chucking ring of the present invention. FIG. 5 (a)
Shows an example of concentration of grasping power ((C) in (b) of FIG. 4). This shows an example of concentration of grasping force when φD <φd.

FIG. 5 (a-1) shows how the chucking ring 1 is tightened with three claws. In this case,
The gripping force by the claws concentrates at the position of the chucking ring 1 marked with an arrow.

FIG. 5 (a-2) shows how the chucking ring 1 is tightened with three claws. In this case,
A frictional force is generated in the direction of the arrow between the chucking ring 1 with the arrow and the surface at the position of the claw, and the surface is scratched.

FIG. 5B shows an example of interference between the claw and the slit ((C) of FIG. 4B), which is φD.
An example of interference between the claw and the slit 2 when> φd is shown. FIG. 5B-1 shows an example of calculating the slit width G. Here, as shown in the drawing, the slit width G = (φD−φd) π, so now, if φD = 27 and φd = 25, then: slit width G = (27-25) π≈6. It becomes 3 (mm).

In FIG. 5B-2, the slit portion is divided into three parts.
It shows how the chucking ring 1 in the slit portion interferes with the nail when tightened with two nails. When φD> φd becomes extremely extreme as described above, the chucking ring 1 in the slit portion may be deformed when it is tightened by the three claws, which may interfere with the claws to prevent the workpiece 3 from being fixed.

FIG. 5 (c) shows an example of friction between the claw and the chucking ring ((D) in FIG. 4 (b)). This is an example of friction between the claw and the chucking ring 1 when φD> φd.

In FIG. 5C-1, the slit portion is 3
Shown when tightening is started with two claws. In this state, the portion “a” of the illustrated claw is in contact with the chucking ring 1.

In FIG. 5C-2, the slit portion is 3
Shown when tightened further with two claws. In this state, the portion b of the illustrated claw is in contact with the chucking ring 1. Therefore, from (c-1) a to (c-
Scraping to the position b in 2) occurs when the chucking ring 1 is tightened by the three claws, and scratches occur at the distance a-b.

FIG. 6 shows an example of actual measurement of roundness. this is,
After the inner surface of the workpiece 3 having the same size as that shown in FIG. 2C is internally ground by the inner surface grinding machine, the roundness of the inner surface is actually measured. FIG. 6A shows an example of the present invention. This is shown in FIG.
A ring-shaped workpiece 3 of sintered ferrite having the dimensions of
2 (b) is inserted into the chucking ring 1, tightened by the chuck of FIG. 2 (a), and inner surface grinding is performed by an inner surface grinding machine. The roundness of the inner surface of the workpiece 3 after the inner surface is ground is actually measured. Here, one scale is 4μ
Therefore, a roundness of 6 μm is obtained here (“O: 6 μm” in the figure represents a roundness of 6 μm).

FIG. 6B shows a conventional example. this is,
As shown in FIG. 8 described above, when the workpiece 3 of FIG. 2 (c) is directly clamped and fixed by the chuck of FIG. 2 (a), and the inner surface is ground with the grindstone of the inner surface grinder of FIG. The roundness of the inner surface of the workpiece 3 is measured. Here, only the roundness of 48 μm can be obtained (“O: 4 in the figure”).
8 μm ”represents a roundness of 48 μm).

As can be seen from the above measurement examples, when the thin work piece 3 is directly tightened by a chuck and the inner surface is ground as shown in FIG. 8, a roundness of only 48 μm can be obtained. However, according to the present invention, when the workpiece 3 is inserted into the chucking ring 1 and indirectly chucked by a chuck and the inner surface is ground, the roundness is 6 μm. I was confirmed.

[0055]

As described above, according to the present invention,
When forming a ring shape by internal grinding, the workpiece 3
Since the inner surface is ground in a state where the tool is inserted into the chucking ring 1 with the slit 2 and then fixed, the chucking ring 1 fixes the workpiece 3 on the surface when fixed by the fixing bracket 4. By tightening, it is possible to uniformly apply force from the outer peripheral surface of the workpiece 3 to fix it. As a result, brittle materials such as ceramics, heavy grinding of low-strength materials, and low-strength shaped workpieces 3 that have been difficult to achieve by the conventional fixing method can be securely and securely fixed, particularly the fixing metal fittings 4. Even if the tightening force by the chuck is reduced to about 80% of the conventional value, the workpiece 3 can be sufficiently fixed and the damage rate can be further reduced. From these, the following effects were obtained.

(1) The occurrence rate of cracks, which poses a problem when the inner surface of a brittle material is ground, is close to 10 to 20% when the conventional chucking ring 1 is not used. By using it, it was possible to suppress it to almost 0%, and productivity was greatly improved.

(2) The accuracy of the work 3 after the inner surface is ground is
The roundness of 48 μm shown in FIG. 6B is 6 by the use of the chucking ring 1 of the present invention.
It could be improved to about μm. This is because the clamping force from the chuck worked on the entire outer circumference of the work piece 3 on a uniform surface, and the efficiency of the grasping force was improved, and the clamping force could be slightly weakened (about 80%).

(3) Even if the thickness of the work piece 3 of sintered ferrite, which is a brittle material, is 2 mm or less, sufficient roundness can be obtained by grinding the inner surface (in the case of FIG. 2 (c)). Has a thickness of (25-21) / 2 = 2 mm after processing, and it is possible to stably and reliably fix the thin-walled workpiece 3 that is difficult to fix by a conventional direct chuck, and to grind the inner surface.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is a diagram (part 1) for explaining a specific example of the present invention.

FIG. 3 is a diagram (part 2) for explaining a specific example of the present invention.

FIG. 4 is an explanatory view (1) of fitting of the workpiece and the chucking ring of the present invention.

FIG. 5 is an explanatory view (No. 2) of fitting of the workpiece and the chucking ring of the present invention.

FIG. 6 is an example of actual measurement of roundness.

FIG. 7 is an example of an inner surface grinding machine.

FIG. 8 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

1: chucking ring 2: slit 3: work piece 4: fixing metal fitting (chuck): fitting example of φD <φd (φD: inner diameter of chucking ring, φd: outer diameter of workpiece): fitting of φD≈φd Fitting example: Fitting example of φD> φd

Claims (3)

[Claims] 1. A workpiece (3) is placed inside a chucking ring (1) having an inside diameter φD which is approximately the same as the outside diameter φd of the workpiece (3) and having a slit (2) in the axial direction. An inner surface grinding method characterized by grinding the inner surface of the workpiece (3) after fixing the chucking ring (1) with a fixing metal fitting (4) in the inserted state. 2. The inner diameter φD of the chucking ring (1)
And the outer diameter φd of the workpiece (3) (φD-φd)
Was set to -0.2 to +0.5 mm, and the inner surface grinding method according to claim 1, wherein 3. The inner surface grinding method according to claim 1, wherein when the work (3) is long, it is divided into a plurality of chucking rings (1).