JP2000084780A - Nc machining machinery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent decline of machining precision near the top of a curved surface by arranging two feed rods with a specific angle relative to the rotary shaft of a work. SOLUTION: This NC machining machinery (CNC lathe) 41 is equipped with a biaxially-driven NC slide 49 for sending a tool 47 relative to a main shaft 45 for checking a work 43. The NC slide 49 has a Z-axis slide 51 for executing feed at an angle of 45 deg. relative to the main shaft 45 and an X-axis slide 53 for executing feed at a slide cross angle of 90 deg. relative to the Z-axis slide 51 and at an angle of 45 deg. relative to the main shaft 45. And an X-axis table 71 moved by the function of an X-axis driving ball screw 67 is loaded on a Z table 63 moved by the function of a Z-axis driving ball screw 59 and a tool rest 73 is loaded on the X-axis table 71, and profiling machining of the work 43 is executed by the tool 47.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an NC machine (a CNC lathe, a CNC grinder, a CNC dressing device, etc.) for contouring an outer surface or an inner surface of a rotary work into a curved surface. The present invention relates to a technique for improving the accuracy of a curved surface, which decreases with reverse rotation.

[0002]

2. Description of the Related Art There is an NC machine for contouring (contouring) the outer or inner surface of a rotating work into a curved surface. The NC processing machine further includes an NC lathe, an NC grinder, an NC dressing device, and the like. For example, an NC lathe is a turning machine that rotates a workpiece and feeds a tool to perform cutting.
ning). In addition, the NC dressing device performs dressing by rotating the grindstone and feeding the dresser to grind the grindstone surface. In recent years, these NC lathes and NC dressing machines have been equipped with computerized numerical control (computerized numerical control).
CNC lathes and CNC dressing machines with a built-in small computer for performing control) are widely used.

For example, this CNC lathe 1 has conventionally been
As shown in the figure, a spindle 5 for chucking the work 3 and a biaxial drive N for feeding a tool 7 in parallel / perpendicular to the spindle 5
A C slide 9 is provided. The NC slide 9 has a Z-axis slide 11 for performing feed parallel to the main shaft 5 and an X-axis slide 13 for performing feed perpendicular to the main shaft 5.

A Z-axis slide 11 is fixed to a bed (not shown) and is parallel to the main shaft 5. The Z-axis slide 11 is disposed parallel to the main shaft 5 and both ends are rotatably supported by ball screw supports 17. Z-axis drive ball screw 19
And a Z-axis driving servomotor 21 for rotating the Z-axis driving ball screw 19, and a Z table 23 slidably supported by the linear guide 15 and driven by the Z-axis driving ball screw 19.

The X-axis slide 13 has the same construction as the Z-axis slide, is fixed on the Z table 23 in a direction perpendicular to the main shaft 5, and rotates an X-axis drive ball screw 27. And a tool rest 33 is attached to the upper surface of the X table 31.

When turning the work 3 into an axisymmetric curved surface, the CNC lathe 1 uses a Z-axis and X-axis drive servomotors 21 controlled by an NC device with respect to a spindle 5 chucking the work 3 to be machined. 29, the Z and X slides 23 and 31 are slid parallel and perpendicular to the main shaft 5 as shown in FIG. Thereby, X slide 3
The work 3 was turned into a desired curved shape by operating the tip of the tool 7 attached to the upper tool post 33 in a curved shape.

[0007]

However, a conventional CNC lathe having a two-axis drive slide that slides parallel and perpendicular to the main shaft described above has a curved surface shown in FIG. When machining a track surface, an X, Z-axis driving servomotor that drives an X, Z-axis driving ball screw near the vertex of the curved surface (in the above-described conventional example,
The X-axis driving servomotor) performs the reversing operation. That is, quadrant switching of the control axis is performed, and there is a problem that the curved surface accuracy is deteriorated by this operation. In contrast, each N
Manufacturers of C-apparatus are striving to improve the accuracy deterioration due to such quadrant switching by devising a control system. However, near the vertex of this surface, one of the two slides changes from forward to backward, so backlash generated in the mechanical feed system is inevitable, and there is a limit to improving the accuracy near the vertex of the surface. Was. For example, when the finishing of the raceway surface of a ball bearing is performed by a CNC lathe, a quadrature switching causes a shape error 35 (FIG. 16) of several μm, and it is not possible to turn a high-precision ball bearing. The present invention has been made in view of the above circumstances, and when machining an axisymmetric curved surface shape, it is possible to prevent a decrease in machining accuracy near the apex of the curved surface.
It is intended to provide a C processing machine.

[0008]

An NC processing machine according to the present invention for achieving the above object provides a tool rest, which is supported by two feed shafts, with respect to a rotated workpiece. An NC machine for contouring an outer surface or an inner surface into a curved shape, wherein each of the two feed shafts is
It is characterized by being arranged at an angle of 45 ° or more and 90 ° or less with respect to the rotation axis of the work.

In this NC processing machine, each of the two feed shafts is arranged at an angle of not less than 45 ° and not more than 90 ° with respect to the rotation axis of the work, so that the number of control axes increases in the middle. Since the decrease or the decrease does not reverse the increase, it is not necessary to switch the quadrants in the contour processing of the curved surface, and the accuracy problem associated with this does not occur.

In the NC machine, it is preferable that an angle formed between the two feed shafts is equal to or smaller than an angle at which tangents at both ends of the arc intersect.

In this NC processing machine, each of the two feed shafts is disposed at an angle of not less than 45 ° and not more than 90 ° with respect to the rotation axis of the workpiece, and the angle formed by the two feed shafts is different. Is set to be equal to or smaller than the angle at which the tangents at both ends of the arc intersect, and all inversions of the control axis that can occur when the angle between the two feed axes is greater than the angle at which the tangents at both ends of the arc intersect are eliminated. .

Further, in the NC processing machine, an angle formed between the two feed shafts may be 90 ° or less.

In this NC processing machine, the angle between the two feed axes is set to 90 ° or less, so that the curved surface processing in which the normal change angle of the curved surface to be processed is 90 ° or more can be performed on the control axis. It can be done without the need for quadrant switching.

Further, in the NC machine, it is preferable that an angle between the two feed shafts is not less than 60 ° and less than 90 °.

In this NC machine, since the angle formed between the two feed shafts is set to be not less than 60 ° and less than 90 °, it is not necessary to secure a high feed accuracy, and no inflection point is generated. The practical groove design condition is satisfied.

Further, in the NC processing machine, an angle formed between each of the two feed shafts and a rotation axis of the workpiece may be different.

This NC machine is capable of coping with the ball groove R finishing, for example, for an angular ball bearing, in which the shape of the ball groove R is formed asymmetrically with respect to the axis perpendicular to the rotation axis, without switching the quadrant.

Further, the NC processing machine provides an NC processing machine which feeds a dresser supported by two feed shafts to a rotated grindstone to contour the outer or inner surface of the grindstone into a curved surface shape. The two feed shafts may be arranged at an angle of 45 ° or more and 90 ° or less with respect to the rotation axis of the whetstone.

In this NC processing machine, the above-mentioned N
As in the case of the C processing machine, the control axis does not reverse from increasing to decreasing or from decreasing to increasing, making it unnecessary to switch quadrants in the contour processing of curved surfaces, enabling accurate transfer of the ball groove R shape to the grinding wheel with high accuracy. Become.

Further, in the machining method of the NC machining machine, a feed is provided to a tool rest supported by two feed shafts for a rotated work, and an outer surface or an inner surface of the work is contoured into a curved shape. In the machining method of the NC machining machine, each of the two feed shafts is disposed at an angle of 45 ° or more and 90 ° or less with respect to the rotation axis of the workpiece, and the tool rest is moved by the two feed axes. The workpiece is fed in a direction synthesized by the respective feed directions of the shaft, and the outer surface or the inner surface of the work is contoured into a curved shape by a tool attached to the tool post.

In the machining method of the NC machine, the control axis does not reverse from increasing to decreasing or decreasing to increasing in the middle, so that it is not necessary to switch quadrants in contour machining of a curved surface. As a result, there is no mechanical backlash near the apex of the axisymmetric curved surface which cannot be avoided in the prior art.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an NC machine according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view showing a configuration of a first embodiment of a CNC lathe according to the present invention. As shown in FIG. 1, an NC processing machine (CNC lathe) 41 according to the present embodiment includes a spindle 45 for chucking a workpiece 43 and a tool 47 for the spindle 45.
And an NC slide 49 driven by two axes. The NC slide 49 forms a Z-axis slide 51 for feeding at an angle of 45 ° with respect to the main shaft 45, forms a 90 ° slide crossing angle with the Z-axis slide 51, and Axis slide 5 which feeds at an angle of 45 °
And 3.

The Z-axis slide 51 has a linear guide 55 fixed to a bed (not shown), and a Z-axis driving member disposed in parallel with the linear guide 55 and having both ends rotatably supported by ball screw supports 57. A ball screw 59, a Z-axis driving servomotor 61 for rotating the Z-axis driving ball screw 59, and a Z that is slidably supported by the linear guide 55 and driven by the Z-axis driving ball screw 59.
And a table 63.

The X-axis slide 53 has a linear guide 65 fixed to the Z table 63 and an X-axis driving ball screw disposed in parallel with the linear guide 65 and having both ends rotatably supported by ball screw supports 66. 67, an X-axis driving servomotor 69 for rotating the X-axis driving ball screw 67, and an X driven by the X-axis driving ball screw 67 slidably supported by the linear guide 65.
It comprises a table 71 and a tool rest 73 attached to the upper surface of the X table 71. Note that γ in FIG. 1 indicates an angle between each of the two feed shafts and the main shaft 45, and β indicates a slide intersection angle at which the two-axis slide drive shaft intersects. In the present embodiment, β is 90 ° and γ is 45 °.

Next, the CNC lathe 4 configured as described above
1 will be described. FIG. 2 shows a diagram for explaining the increase and decrease of the moving tool coordinate value when the arc angle of the groove R is 90 ° or less. In FIG. 2, A is the outer diameter of the ball bearing internal transfer and the contour of the ball groove R portion, and B is the inner diameter of the ball bearing outer ring and the contour of the ball groove R portion.

Here, assuming that the arc angle of the ball groove R portion is 2φ and the angle between the tangents at both ends of the ball structure R portion is α, (1)
The relationship of the expression holds. α = π−2φ (1) Here, from the relationship of equation (1) and 2φ ≦ 90 °, β (9
0 °) ≦ α, so that the X slide axis and the Z slide axis can be machined with clearly monotonous increase / decrease control during the contouring of A.

That is, the number of control axes decreases from an increase during machining,
Or, it does not reverse from increasing to decreasing. Therefore, in the contour processing of A, the quadrant switching is not required, and there is no precision problem associated therewith. Similarly, in the contour processing of B, it is not necessary to switch the quadrants, and there is no precision problem associated therewith. For example, if the slide intersection angle β is 90
When 2φ is 90 °, α becomes 90 °,
Since the condition of β ≦ α is satisfied, processing can be performed with high accuracy.

Therefore, in the CNC lathe 41, the X-axis slide 53 and the Z-axis slide 53, Z are used for machining in which the normal change angle of the axisymmetric curved surface is 90 ° or less (for example, equivalent to 2φ ≦ 90 ° in the ball bearing inner ring of FIG. 3). By arranging the drive shaft of the shaft slide 51 so as to be at 45 ° with respect to the main shaft 45, curved surface processing can be performed with high accuracy without switching quadrants of the control shaft.

FIG. 4 is an explanatory diagram of a ball groove machining method for the inner race of the ball bearing by the CNC lathe of this embodiment. As shown in FIG. 4, the end surface A1, the outer diameter and the raceway surface A of the ball bearing internal transfer.
In the machining of No. 2, A1 is a linear interpolation operation of the X and Z axes, and A2 is a straight line, circular arc, linear interpolation operation to drive each slide axis to perform the machining. In this case, since the control axis does not need to be reversed, machining on an ideal curved surface without switching quadrants, which is impossible with a conventional two-axis control lathe, is possible.

FIG. 5 is an explanatory view of a ball groove machining method for the outer race of the ball bearing by the CNC lathe according to the present embodiment. As shown in FIG. 5, when the end face B1, the outer diameter, and the raceway surface B2 of the ball bearing external transfer are processed, the same processing as that of the internal transfer can be performed. That is, B1 is a linear interpolation operation of the X and Z axes, and B2 is a linear, arc, and linear interpolation operation for driving each slide axis to perform machining. Since the control shaft does not need to be reversed, machining on an ideal curved surface without switching quadrants, which is impossible with a conventional two-axis control lathe, is possible.

Therefore, according to the above-mentioned CNC lathe 41,
There is no mechanical backlash due to the back-and-forth movement near the top of the curved surface at the time of turning the axisymmetric curved work, which cannot be avoided by the conventional technology, and it is possible to prevent the accuracy from being deteriorated near the top of the curved surface.

Next, a second embodiment of the NC machine according to the present invention will be described. FIG. 6 shows a second embodiment of the CNC lathe according to the present invention.
It is a top view showing an embodiment. As shown in FIG. 6, the NC processing machine (CNC lathe) 81 according to the present embodiment includes a spindle 45 for chucking the work 43 and a two-axis driven NC slide 49 for feeding a tool 47 to the spindle 45. .
In the NC slide 49, the intersection angle β between the Z-axis slide 51 and the X-axis slide 53 is set to β <90 °. Other configurations are the same as those of the CNC lathe 41 described above.

Next, the operation of the CNC lathe 81 will be described. FIG. 7 is a view for explaining an increase or decrease of the moving tool coordinate value when the arc angle of the groove R is equal to or larger than 90 ° and smaller than 180 °. According to FIG. 7, in the present embodiment, it is possible to process a workpiece 43 having a ball groove depth deeper than in the case of FIG. At this time, the condition is that the slide intersection angle β satisfies β ≦ α, as will be apparent from the following description.

First, as shown in FIG.
Assuming that the angle between the x-axis and the X-axis and the angle between the z-axis and the Z-axis are θ with respect to z and the sliding directions X and Y, θ = 45 ° − (β / 2) (2)

Here, a correlation diagram between the x and z axes orthogonal to FIG. 8 and the X and Z axes inclined with respect to the x and z axes is shown. According to FIG. 8, z = Zcos θ + Xsin θ (4) Since x = Zsin θ + Xcos θ (5), sin (θ) is given by equation (4), and cos θ is given by equation (5).
When multiplied by, zsinθ = Zcosθ · sinθ + Xsin 2 θ (6) xcosθ = Zsinθ · cosθ + Xcos 2 θ (7) , and the Subtracting further (6) from (7), zsinθ-xcosθ = X (sin 2 θ- cos ² θ) (8) That is, X can be represented by X = (xcos θ−z sin θ) / (cos ² θ−sin ² θ) (9) Similarly, Z is expressed as follows: Z = (z cos θ−x sin θ) / (cos ² θ−sin) ² theta) can be expressed by (10). Therefore, for the X and Y axes,
What is necessary is just to control by the value converted by Formula (9) and (10).

Here, in the path of S → T → U shown in FIG. 9, the condition that X continues to decrease in the range of Xs → Xt → Xu is based on the tangent g of S point and the tangent g of S point. it is a condition angle formed [psi ₁ with the z-axis is large. That is, the inclination ψ _{1 of the} tangent g is ψ ₁ = ψ (π / 2) −φ｝ + ｛(β / 2) + θ｝ (11), and the inclination of the X axis with respect to the z axis is β + θ. ｛(Π / 2) −φ｝ +｝ (β / 2) + θ｝ ≧ β + θ∴β ≦ π−2φ (12) Since π−2φ is equal to α, Equation (13) is eventually the condition. β ≦ α (13)

Similarly, with respect to the Z coordinate, the condition that z continues to increase in the range of Zu → Zt → Zs in the path of S → T → U is based on the slope of the Z axis with respect to the x axis. it is a condition angle formed [psi ₂ between the tangent line f and the x-axis is large. Therefore, the equation (13) is also satisfied for the condition for increasing Z.

This will be additionally described with reference to FIGS. 10 and 11. FIG. 10 shows that the slide intersection angle β is π
FIG. 11 is a diagram illustrating an increase and a decrease in the X and Z values when the slide intersection angle β is smaller than π−2φ. Note that the same members as those shown in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted. First, β> π shown in FIG.
In the case of −2φ, for example, when contouring the shape of A using the slide axes Z and X, points Z1 to P8 corresponding to P1 to P8 when contouring continuously from the arc portions P1 to P8.
Consider Z8 and the coordinates of X1 to X8. In this case, FIG.
As is clear from the above, P1 → P2 → P3 →... → P7
→ The increment of the X and Z coordinates of P8 is as shown in Table 1.

[0039]

[Table 1]

That is, the increment of Z is inverted between P1 and P3, and the quadrant switching of the feed drive system occurs. Similarly,
During the period from P6 to P8, the increment of X 'is inverted, and a quadrant switching of the feed drive system occurs. That is, when β> π−2φ, backlash occurs due to switching of quadrants, and a reduction in processing accuracy is inevitable.

On the other hand, when β ≦ π−2φ shown in FIG.
For example, when contouring the shape of A with slide axes Z and X, points Z1 to Z6 corresponding to P1 to P6 when contouring continuously from arc portions P1 to P6, and X1 to X6
Consider the coordinates of X6. In this case, as is apparent from FIG. 11, X, Z of P1 → P2 → P3 →... → P5 → P6
The coordinate increments are as shown in Table 2.

[0042]

[Table 2]

That is, the increments of Z and X between P1 to P6 are uniform without switching between positive and negative. Therefore, no quadrant switching of the feed drive system occurs. That is, β ≦ π−2φ
When the slide having the relationship of (1) is used, quadrant switching does not occur, and high-precision processing becomes possible.

In this x, z coordinate system, β ≦
As long as the relationship of π-2φ (β ≦ α) is satisfied, the same effect as in the first embodiment can be obtained. For example, 2φ =
Since α = 60 ° in the case of 120 °, β ≦ 60 ° may be set. At this time, if β = 60 °, it is not necessary to switch the quadrants in the X and Z slide axis control during the contour processing of the ball groove R, and the associated precision failure does not occur (the angle formed by both slide drive shafts and the main shaft). γ is 60 °).

Therefore, according to the CNC lathe 81, by setting the slide intersection angle β to 90 ° or less and making the main shaft axis direction and both slide drive shaft directions appropriate, the normal line change angle of the curved surface to be processed is 90 °.曲 The above-mentioned curved surface processing can be performed without the necessity of switching the quadrant of the control axis.

Note that β and 2φ have the following relationship because β ≦ π−2φ. [Β] [2φ] 0 ゜ 180 ゜ or less 30 ゜ 150 ゜ or less 60 ゜ 120 ゜ or less 90 ゜ 90 ゜ or less 180 ・ 0 ゜ or less

Here, the theoretical range of the CNC lathe is 0 <
Since β ≦ 90 °, 2φ is in the range of 90 ° to 180 °. The following is considered as the lower limit value of β. That is, when β is sufficiently smaller than 90 °, high feed accuracy is required. This is because it is difficult to control the amount of slide movement because the linearly moving component of the two-axis slide approaches the feed amount of the tool. Further, the practical range of 2φ is only required to cover up to about 120 °. On the other hand, the following is considered as the upper limit value of β. That is, if the angle exceeds 90 °, 2
φ becomes 90 ° or less, and the practical groove design condition is not satisfied. From these facts, the angle β between the two feed axes is
Is preferably 60 ° or more and less than 90 °.

Next, a third embodiment of the NC machine according to the present invention will be described. FIG. 12 is a plan view showing a third embodiment of the CNC lathe according to the present invention, and FIG. 13 is an enlarged view of a processing portion shown in FIG. Note that the same members as those shown in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

As shown in FIG. 12, an NC machine (CNC lathe) 91 according to this embodiment sets an angle γ between both slide drive shafts and the main shaft 45 of the CNC lathe 41 according to the first embodiment. It is an asymmetric lathe. That is, the angle between each of the two feed shafts and the main shaft 45 is γ1 and γ
There are two different things. Another configuration is the CN described above.
It is the same as the C lathe 41.

According to the CNC lathe 91, by disposing the two slide drive shafts asymmetrically, for example, the ball groove R shape as shown in the STU R shape of FIG. It is possible to cope with the finishing of the ball groove R such as the angular ball bearing 95 formed asymmetrically with respect to the orthogonal axis without switching the quadrant.

Next, a fourth embodiment of the NC machine according to the present invention will be described. Although not shown, the NC processing machine according to this embodiment is configured as a dressing device for a ball bearing ball groove R grinding machine in which the work 43 is replaced with a grindstone and the tool 47 is replaced with a dresser. That is, a feed is given to a dresser supported by two feed shafts for the rotated grindstone, and the outer surface or the inner surface of the grindstone is contoured into a curved shape. Also in this dresser, as in the case of the NC machine described above, each of the two feed shafts is arranged at an angle of 45 ° to 90 ° with respect to the rotation axis of the grindstone. According to this NC processing machine (dresser),
An accurate ball groove R shape can be transferred to a grindstone without switching quadrants.

[0052]

As described in detail above, the NC machine according to the present invention arranges each of the two feed shafts at an angle of 45 ° to 90 ° with respect to the rotation axis of the work. Since it is provided, turning, grinding, and grinding stone dressing of the ball groove R portion of the ball bearing can be performed without switching the quadrant of the NC slide, and the slide back and forth movement near the vertex of the curved surface, which is inevitable in the conventional technology. Eliminates mechanical backlash. As a result, it is possible to avoid a machining shape error due to the quadrant switching, and to prevent a decrease in accuracy near the top of the curved surface.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of a CNC lathe according to the present invention.

FIG. 2 is a diagram for explaining an increase or a decrease in coordinate values of a moving tool when an arc angle of a groove R is smaller than 90 °.

FIG. 3 is an explanatory diagram of an arc angle at the time of processing a ball groove R of a ball shaft inner race.

FIG. 4 is an explanatory view of a ball groove machining method for an inner race of a ball bearing by the CNC lathe according to the first embodiment.

FIG. 5 is an explanatory diagram of a ball groove machining method for a ball bearing outer ring by the CNC lathe according to the first embodiment.

FIG. 6 is a plan view showing a second embodiment of the CNC lathe according to the present invention.

FIG. 7 is a diagram for explaining an increase and a decrease in the moving tool coordinate value when the arc angle of the groove R is equal to or larger than 90 ° and smaller than 180 °.

FIG. 8 is a correlation diagram between orthogonal x and z axes and X and Z axes inclined with respect to the z and z axes.

FIG. 9 is a diagram illustrating conditions for increasing and decreasing X and Z values on the X and Z axes.

FIG. 10 is a diagram illustrating an increase and a decrease in X and Z values when the slide intersection angle is larger than π−2φ.

FIG. 11 shows X, when the slide intersection angle is π−2φ or less.
It is a figure explaining increase and decrease of Z value.

FIG. 12 is a plan view showing a third embodiment of the CNC lathe according to the present invention.

FIG. 13 is an enlarged view of the processing section shown in FIG.

FIG. 14 is a plan view showing a conventional CNC lathe.

FIG. 15 is an enlarged view of a processed portion shown in FIG.

FIG. 16 is a sectional view of a ball bearing raceway surface processed by a conventional CNC lathe.

[Explanation of symbols]

 43, 95 Work 73 Tool post 41, 81, 91 NC machine

Claims (1)

[Claims] 1. An NC machine for feeding a rotated work to a tool rest supported by two feed shafts and contouring an outer surface or an inner surface of the work into a curved shape. An NC machine wherein each of the feed shafts is disposed at an angle of 45 ° or more and 90 ° or less with respect to the rotation axis of the workpiece.