JP3071640B2 - Deep hole inner surface grinding method for workpieces - 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 grinding the inner surface of a deep hole in a workpiece, and more particularly, to a method for grinding an inner surface of a deep hole in a workpiece by grinding load of the workpiece. Related to internal grinding technology.

[0002]

2. Description of the Related Art Workpieces (hereinafter referred to as inner diameter surfaces of bearings, etc.)
Generally, in an internal grinding machine that grinds the inner diameter surface of a hole of a work, the work is supported and rotated by a work headstock, and a grindstone is inserted into a machining hole of the work from an open side to grind the inner diameter surface. Process.

By the way, in the case of a so-called deep hole in which the processing hole is long in the axial direction, since the processing length is longer than that of a grinding wheel, conventionally, the grinding wheel is reciprocated (oscillated) in the axial direction of the processing hole. Oscillate grinding, in which cutting is performed while cutting, is generally performed.
It was performed throughout the entire grinding process, from rough grinding, which is rough finishing, to fine grinding, which is finishing.

[0004]

However, in such a conventional deep hole inner surface grinding method, as the depth of the machined hole becomes longer, the effect of the cutting speed and the sharpness of the grindstone results in the influence of the work. Due to bending, the taper amount of the machined hole increased (at the time of rough grinding), and it took time to correct the taper amount (at the time of fine grinding).

[0005] This point will be described below with reference to FIGS. 5 to 7. In these figures, the amount of deformation is shown to be greatly enlarged as compared with the actual case in order to facilitate understanding.

[0006] The direction of oscillation of the grinding wheel and the axis of the workpiece
When the centers are parallel: (See FIGS. 5 and 6) The flange Wa of the work W is rotated while being chucked and supported by chuck jaws a, a,. The grindstone G attached to the grindstone shaft b of the table is inserted into the machining hole Wb of the work W to grind the inner diameter surface I thereof. c denotes a stopper that determines the axial position of the workpiece W during chucking.

In this case, the grindstone G cuts in the radial direction of the machining hole Wb while oscillating in a direction parallel to the axis X of the work W.
Since the workpiece W is supported in a cantilever manner while the grinding load P (cutting direction) is constantly acting on the workpiece W, the workpiece W is processed at the time of supporting side processing (FIG. 5B and FIG. 6).
(See (a)) and during processing on the non-support side (Fig. 5 (a) and Fig. 6 (b)
The work W is bent in the cutting direction as shown in the drawing at the time of processing on the non-support side (the amount of bending δ =
PL ³ / 3EI, L: work length, E: longitudinal elastic modulus,
I: second moment of area).

As a result, when the rough grinding is completed, a residue corresponding to the above-mentioned bending amount δ with respect to the set depth of cut is generated on the processing surface I of the work W, and the cross section of the grinding locus with respect to the axis X is generated. It has a tapered shape with a gradient.

Therefore, the set fine polishing finish dimension (diameter) is D ₀ , and the set rough polishing processing dimension (diameter) is D 0.
₁ and the remaining tapered rough grinding dimension (diameter) is D ₂
(D ₂ = D ₁ in the support side, the counter support side D ₂ <D ₁₎ When the actual machining allowance D during fine grinding is expressed by the following equation. D = (D ₀ −D ₁ + D ₂ ) / 2

[0010] The remaining amount of the tapered rough polishing is
The longer the processing length, the greater the amount. The actual machining allowance D at the time of fine grinding increases due to the amount of unfinished polishing remaining added to the preset fine machining allowance (set fine machining allowance). During the grinding, the grinding time of the entire grinding process is greatly lengthened.

By the way, in this case, the grinding load value by the grindstone G is reduced to perform grinding with a value that does not affect the deflection of the work W, so that the cylindricity of the machined hole Wb of the work W is determined by the oscillation motion direction and the work axis. It is good because X is parallel.

[0012] The direction of oscillation of the grinding wheel and the axis of the workpiece
When the center is inclined : (see FIG. 7) As described above, the work W is bent by the grinding load P during the non-support side processing. Therefore, in consideration of the amount of deflection δ, as shown in FIG. 7A and FIG.
When the axis X of the grinding wheel G is inclined by θ with respect to the direction of the oscillating motion of the grinding wheel G, the grinding load P of the grinding wheel G becomes the cutting speed,
When the sharpness of the grindstone G is constant, and when the unit length of the grindstone and the removal volume per unit time are constant, it does not change. There is no leftover for the set depth of cut, and the cross section of the grinding trajectory has a cylindrical shape parallel to the axis X.

However, at the transition between the rough grinding and the fine grinding, the grinding load P changes (generally, the grinding load P
Is the time of coarse grinding> the time of fine grinding), and as shown in FIG. 7 (c), the inclination angle θ of the axis X of the work W is set in accordance with the amount of deflection of the work W due to the grinding load P during fine grinding. Then, at the time of rough grinding, the work W is bent as shown by the solid line. As a result, the machining surface I of the work W is left behind with respect to the set depth of cut, and the grinding locus cross section has a tapered shape having a gradient with respect to the axis X.

[0014] By the taper-shaped rough polishing unremoved amount (remaining taper amount / 2 due to the difference in grinding load between rough grinding and fine grinding) δ ', the actual allowance D during fine grinding is:
The longer the processing length, the greater the number of times, and also the time required for precision grinding and, consequently, the entire grinding process is greatly increased.

Further, at the time of spark-out after the completion of fine grinding, the cylindricity of the processing hole Wb is determined by the balance between the deflection reaction force of the work W and the grinding load P, and immediately after entering the spark-out and immediately before the end of the spark-out. In this case, the grinding load P changes, and if the sharpness of the whetstone changes immediately before and after the dressing, the grinding load P also changes slightly, which makes it difficult to control the cylindricity.

The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide an internal grinding machine for grinding an inner surface of a deep hole, which takes into account the bending caused by the grinding load of a work. An object of the present invention is to provide a method of grinding a deep hole inner surface of a workpiece, which can reduce a residual amount of rough grinding and reduce a grinding time by grinding.

[0017]

In order to achieve the above-mentioned object, a method of grinding the inner surface of a deep hole of a work according to the present invention comprises rotating a work in a cantilever manner while rotating the inner surface of the deep hole of the work with a grindstone. In the internal grinding to grind, in the rough grinding process,
Plunge grinding is performed several times on the inner surface of the deep hole at predetermined intervals in the axial direction of the work, and in the fine grinding process, oscillating grinding is performed over the entire length of the inner surface of the deep hole where the plunge grinding was performed. And

In this case, in the plunge grinding at the time of rough grinding, a plurality of plunge workings are performed at predetermined intervals in the axial direction of the work with a grindstone shorter than the working length of the deep hole of the work. It is preferable that the depth of cut in the processing is sequentially changed in proportion to the amount of deflection of the workpiece due to the grinding load.

Further, the depth of cut in each plunge processing is set so that the cross section of the grinding trajectory of the inner surface of the deep hole at the time of completion of the rough grinding has a substantially uniform sawtooth shape in the axial direction. It is preferable to set the number of plunge processing and the depth of cut so that the inner diameter difference between the peak and the valley in the cross section of the grinding locus falls within a predetermined range.

[0020]

When grinding the inner surface of a deep hole according to the present invention, plunge grinding is performed a plurality of times on the inner surface of the deep hole during rough grinding, and this plunge grinding is performed during subsequent fine grinding. Oscillate grinding is performed over the entire length of the inner surface of the deep hole.

That is, in the rough grinding in which the grinding load of the grindstone is large, the work supported and rotated in a cantilever form naturally bends. Preferably, the cutting amount in plunge grinding at each of these axial positions is sequentially changed in proportion to the amount of deflection of the work due to the grinding load, so that the workpiece machining diameter after the coarse grinding can be changed in the axial direction. The position is also kept within a predetermined size range.

Thus, the actual machining allowance at the time of the fine grinding is set to a necessary minimum, and the oscillating grinding time at the time of the fine grinding is shortened as much as possible.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a deep hole inner surface grinding machine according to the present invention, which comprises a work headstock 1 for supporting and rotating a work W and a grindstone head 2 provided with a grindstone G as main parts.
It is provided with a control device 4 mounted thereon and for controlling the driving thereof.

The work headstock 1 is disposed on the upper surface of the bed 3. The work spindle 5 is rotatably supported by a drive source (not shown), and chucks and supports the work W at its tip. A chuck 6 is mounted. Further, a stopper 7 for defining the axial position of the workpiece W in relation to the chuck 6 is provided at the tip of the workpiece spindle 5.
(See FIGS. 2 to 4).

Then, the chuck claw 6 of the chuck 6
The workpiece W chucked at a, 6a,... (in the illustrated embodiment, the collar Wa is chucked)
The work main shaft 5 is rotatably supported at a predetermined rotation speed.

The grindstone table 2 is provided on first and second tables 10 and 11 arranged on the upper surface of the bed 3. The first table 10 is provided with a work spindle 5 of the grinding wheel head 2.
And is linked to a reciprocating drive source such as a hydraulic cylinder (not shown). The second table 11 is provided so as to be slidable in a direction perpendicular to the axial direction of the work spindle 5, and is linked to a reciprocating drive source (not shown) such as a hydraulic cylinder.

The grindstone head 2 fixed to the upper surface of the second table 11 has its grindstone shaft (quill) 12 rotatably supported in association with a drive source (not shown), and has a work spindle 5 of the grindstone head 2. In the axial direction of the workpiece W, that is, in the axial direction of the workpiece W, and a grindstone G is attached to the tip thereof. As the grindstone G, a processing hole W of the work W is used.
A length shorter than the processing length (length in the axial direction) of b is used.

The grindstone G is driven to rotate at a predetermined number of revolutions by the grindstone table 2, and is moved in the axial direction with respect to the workpiece W by the movement of the tables 10 and 11, while moving in the radial direction. Be cut.

The control device 4 controls the work headstock 1 and the grindstone head 2, specifically, the drive sources of the work spindle 5, the chuck 6, the tables 10 and 11 and the grindstone shaft 12 in synchronization with each other. . The control device 4 includes a CPU, ROM, RA
A CNC control device provided with an M and I / O ports and the like. First, a processing hole Wb of a work W is roughly ground to form a grinding trajectory cross section as shown in FIG. After grinding so as to have a saw-tooth shape, the above-described components for finishing the cylindrical surface as shown in FIG. 2B by fine grinding are controlled. Specifically, the following grinding method is used. Configured to run.

A. Rough grinding: (see FIG. 3) Plunge processing is performed a plurality of times at predetermined intervals in the axial direction of the work W by the grindstone G.

That is, as shown in FIGS. 3 (a) and 3 (b),
By moving the grindstone G in the direction of the axis X of the workpiece W, the plunge processing is performed by sequentially changing the processing position. As an example, the plunge machining number n in this case is calculated by B / L, where B is the length of the grindstone G and L is the length of the work, and the calculated value is obtained by rounding up the decimal point. Numerical values are employed, and in the illustrated embodiment, plunge processing is performed three times.

The cutting amount λ in each of these plunge processes is sequentially changed in proportion to the bending amount δ of the work W due to the grinding load P.

In the illustrated embodiment, the cutting amount (radial cutting forward end position) λ of the grindstone G is changed from the support side (the flange Wa side) of the work W to the opposite support side of the work hole Wb. The increase is performed by the amount by which the work W is gradually bent in the direction in which the inner diameter increases.

More specifically, the controller 4 gives the command value for the cutting of the grindstone G by back calculation. That is, at the plunge processing positions I, II, and III by the respective grindstones G, the respective bending amounts δ ₁ (= 0), δ ₂ , and δ ₃ of the work W are grasped in advance, and the correction value Δ ₁ according to the bending amount is obtained. (= 0), Δ ₂
(= Δ ₂ −δ ₁ ), Δ ₃ (= δ ₃ −δ ₂ ) is added to a predetermined depth of cut λ _0, and a cut command value λ ₁ (= λ ₀ ), λ
₂ (= λ ₀ + Δ ₂ ) and λ ₃ (= λ ₀ + Δ ₃ ).

In this embodiment, the depth of cut λ in each plunge process is determined by
In other words, in a state where the workpiece W is released from the grinding load P and is no longer bent, the cross section of the grinding trajectory of the inner diameter surface I of the machined hole becomes substantially uniform in the axial direction as shown in FIG. It is set as follows. In addition, the deformation | transformation amount of the workpiece | work W and the sawtooth-shaped cross section in FIGS. 2-4 are greatly expanded compared with the actual case for easy understanding.

Further, the plunge machining number n and the cutting depth are also:
The inner diameter difference between the peak portion (the minimum dimension portion set in the rough grinding) 20 and the valley (maximum dimension portion set in the rough grinding) 21 in the sawtooth-shaped grinding locus cross section is set so as to fall within a predetermined range. . As an example, the inner diameter of the valley 21 is set to be near the reference inner diameter of the allowance for fine polishing at the start of fine grinding.

B. Fine grinding: (Refer to FIG. 4) After the rough grinding is completed, the grindstone G is applied to the workpiece W as shown in FIG. While reciprocating (oscillating motion) in the direction of the axis X, a predetermined amount of cuts are made in the radial direction of the processing hole Wb to perform fine grinding, and after a predetermined time of spark-out, a cylinder as shown in FIG. Get a face.

The depth of cut at the time of this fine grinding is set so as to grind the above-mentioned saw-tooth-like ungrinding remaining amount γ ₁ and the set fine grinding allowance γ ₂ . The grinding load P in the fine grinding is smaller than that in the rough grinding, and the amount of deflection of the work W is so small that it can be ignored.

However, according to the above-described grinding method of the present invention, in the rough grinding in which the grinding load P of the grindstone G acts greatly, the work W supported and rotated in a cantilevered manner naturally generates bending. However, the plunge grinding is performed three times while sequentially changing the processing position in the axial direction, and the cutting amount in the plunge grinding at each axial position is determined by the grinding load P.
The workpiece diameter after rough grinding can be kept within a predetermined dimensional range at any position in the axial direction by sequentially changing in proportion to the amount of bending of the workpiece W due to the actual machining allowance during fine grinding. By setting it to the minimum necessary, it is possible to shorten the oscillating grinding time during precision grinding as much as possible.

That is, in the present embodiment, the length of the work W is smaller than the remaining taper amount (rough unremoved amount) due to deflection of the work caused by oscillating grinding at the time of rough grinding in the conventional grinding method. Regardless, the actual allowance for fine grinding can be set to the minimum necessary, so that the time required for oscillating grinding at the time of fine grinding can be significantly reduced as compared with the conventional method. .

The above-described embodiment merely shows a preferred embodiment of the present invention, and the present invention is not limited to this, and various design changes can be made within the scope.

For example, in the illustrated embodiment, the plunge processing is performed three times. However, the plunge processing can be appropriately increased or decreased according to the length of the processing hole Wb of the work W or the like. That is, in general, the number of plunge processings n is calculated by a calculation formula as in the illustrated embodiment, but is not necessarily limited to this. In short, the fine grinding time after the coarse grinding is minimized in relation to the depth of cut. Can be set appropriately so that

Therefore, the shape and dimensions of the cross section of the grinding trajectory on the inner diameter surface I of the processed hole Wb after the rough grinding are not limited to the illustrated embodiment, but can be variously changed. In short, the unsawed amount of sawtooth-like rough grinding after the completion of rough grinding γ
_An optimum grinding locus cross-sectional shape and size are obtained in consideration of the reduction of the precision grinding time due to the reduction of ₁ and the effect of the rough grinding time on the overall grinding time.

In the illustrated embodiment, since the flange Wa, which is the support side, is located on the back side with respect to the grindstone G, the cut amount of the grindstone G is increased toward the right side of the drawing. As shown in FIG. 6, when the flange Wa is supported in the state of coming to the grindstone G side, the cut amount of the grindstone G is reduced as going to the right side in the drawing.

Further, the work W is not limited to a work with a flange as shown in the figure, and other similar cylindrical work having a deep hole can be ground.

Further, in the illustrated embodiment, the rough grinding step and the fine grinding step are performed by one internal grinding machine. For example, in a mass production line or the like, each step of the rough grinding step and the fine grinding step is performed. It is also possible to use separate internal grinding machines.

[0048]

As described in detail above, according to the present invention,
When grinding the inner surface of the deep hole of the work, in the rough grinding process in which the grinding load of the grindstone acts greatly, plunge grinding is performed multiple times at predetermined intervals in the axial direction of the work on the inner surface of the deep hole. Oscillate grinding is performed over the entire length of the inner surface of the deep hole where plunge grinding has been performed, so the amount of unremoved roughing is significantly reduced compared to the conventional method, and the actual machining allowance during fine grinding is minimized. , And the oscillating grinding time at the time of precision grinding can be reduced as much as possible, and further, the entire grinding time can be reduced.

In particular, although a work that is supported and rotated in a cantilever shape naturally undergoes bending, the cutting amount in plunge grinding at each axial position is sequentially changed in proportion to the amount of bending of the work due to the grinding load. Thus, the workpiece diameter after rough grinding can be kept within a predetermined dimension range at any position in the axial direction, and more efficient fine grinding can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing a deep hole inner surface grinding machine according to one embodiment of the present invention.

FIG. 2 is a plan sectional view for explaining a deep hole inner surface grinding method of the present invention using the same deep hole inner surface grinding machine, and FIG. 2 (a) shows a state of a processing inner diameter surface of a workpiece when rough grinding by plunge grinding is completed. FIG. 2B shows a state of the inner diameter surface of the workpiece when the precision grinding by the oscillating grinding is completed.

FIG. 3 is a plan sectional view corresponding to FIG. 2 for illustrating a procedure of plunge grinding during rough grinding in the deep hole inner surface grinding method.

FIG. 4 is a plan sectional view corresponding to FIG. 2 for illustrating oscillating grinding at the time of precision grinding in the deep hole inner surface grinding method.

FIG. 5 is a plan sectional view for explaining a state of oscillating grinding at the time of rough grinding in a conventional deep hole inner surface grinding method, and FIG. 5 (a) shows a state of grinding a non-support side of a work; FIG. 5B shows a state in which the supporting side of the workpiece is ground.

6 is a plan sectional view for explaining a state of oscillating grinding at the time of rough grinding in another conventional deep hole inner surface grinding method, and FIG. 6 (a) is a state when grinding the support side of a work; FIG. 6B shows a state in which the opposite side of the work is ground.

FIG. 7 is a plan sectional view for explaining a state of oscillating grinding at the time of rough grinding in another conventional deep hole inner surface grinding method. FIG. FIG. 7 (b) shows a state in which the opposite side of the work is ground, and FIG. 7 (c) shows a state in which the support angle of the work corresponds to the amount of bending of the work due to the grinding load during fine grinding. This shows the grinding state of the work when set as follows.

[Explanation of symbols]

W Work G Whetstone Wb Work hole (deep hole) of work I Inner diameter surface of work hole 1 Work headstock 2 Grindstone 4 Control device 5 Work spindle 6 Chuck 10, 11 Table 12 Grinding wheel shaft 20 Crest of inner diameter surface of work hole crude Labs setting minimum dimension part) valleys 21 machined hole inner surface (rough Labs setting maximum dimension unit) depth of cut in the gamma ₁ crude Labs removal failure amount gamma ₂ set fine Labs allowance λ plunging

Claims (3)

(57) [Claims] 1. While rotating a workpiece in a cantilever manner,
In the internal grinding to grind the inner diameter surface of the deep hole of this work with a grindstone, in the rough grinding process, plunge grinding is performed multiple times at predetermined intervals in the axial direction of the work on the inner diameter surface of the deep hole, and in the fine grinding process,
The plunging grinding over the entire length of the deep hole inner surface made to perform oscillating grinding, the plunge grinding at rough grinding, machining length of deep holes in the workpiece
A relatively short whetstone allows a predetermined distance in the axial direction of the workpiece.
Perform plunge machining multiple times with a gap
The depth of cut in each plunge process depends on the grinding load.
A deep hole inner surface grinding method for a workpiece, wherein the depth of the workpiece is sequentially changed in proportion to the amount of deflection of the workpiece. 2. The depth of cut in each plunge process is set so that the grinding trajectory cross-section of the inner surface of the deep hole at the time of completion of rough grinding has a substantially uniform saw-tooth shape in the axial direction. claims inner diameter difference between the crests and valleys in the trajectory cross section so as to fall within a predetermined range, wherein the plunging speed and depth of cut is set
Item 6. The method for grinding a deep hole inner surface of a workpiece according to Item 1 . 3. The oscillating grinding at the time of fine grinding is performed by oscillating a grinding wheel, which is shorter than the machining length of the deep hole of the workpiece, in the axial direction of the deep hole, and moving the grinding stone by a predetermined amount in the radial direction of the deep hole. 3. The depth of the workpiece according to claim 2 , wherein the cutting amount is set so as to grind the uncut amount of the saw-toothed rough grinding and the set fine grinding allowance. Hole inner surface grinding method.