JP3401861B2 - Curved surface processing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curved surface machining method for machining a free-form surface represented by a toroidal surface. 2. Description of the Related Art FIG. 7 shows an example of a workpiece having a three-dimensional free-form surface represented by a toroidal surface. In FIG. 7, reference numeral 1 denotes a workpiece having a toroidal curved surface, and the toroidal curved surface 2 of the workpiece 1 has a curved surface having different curvatures around an axis parallel to the B axis and around an axis parallel to the A axis. are doing. Conventionally, for processing such a toroidal curved surface, a three-axis control type processing machine having a work table moved in the X-axis and Y-axis directions and a disk-shaped grindstone 3 moved in the Z-axis direction. Is used. When a toroidal curved surface of a workpiece is processed using such a processing machine, the workpiece 1
Is moved in the X-axis direction, and the grindstone 3 is cut and fed in the Z-axis direction according to the curved surface shape data to perform one-pass machining. Then, after moving the workpiece 1 by one pitch in the Y-axis direction, the workpiece and the grindstone are again controlled simultaneously in the X-axis and Z-axis directions to perform one-pass machining. Hereinafter, by repeating the same operation, the workpiece is subjected to the curved surface processing according to the curved surface shape data. [0004] However, in the conventional processing machine described above, since the toroidal curved surface is processed by three-axis control, the workpiece 1 is moved in the Y-axis direction when the curved surface is processed. Workpiece 1 when pitch feed
As shown in FIG. 8, the contact direction between the workpiece and the grindstone 3 changes from the center of the processing curved surface 2 in the Y-axis direction to the end. That is, when the grindstone 3 is located at a position shown by a two-dot chain line in FIG. 8 with respect to the workpiece 1, the contact direction (contact point P1) between the workpiece 1 and the grindstone 3 is the grinding stone cutting feed direction (Z axis). 8), the contact direction between the workpiece 1 and the grindstone 3 (the contact point P2) is changed to the direction of the grindstone infeed when the grindstone 3 comes to the position shown by the solid line in FIG. Deviates from the normal 4 of the curved surface 2 corresponding to the angle θ1. As a result, a deviation corresponding to θ1 occurs between the processing position of the curved surface controlled by the NC shape data of the curved surface and the actually processed position, which adversely affects the accuracy of generating the curved surface.
Further, when the grinding wheel 3 is cut and fed in the Z-axis direction while moving the workpiece 1 in the X-axis direction during the curved surface machining, the workpiece 1
As shown in FIG. 9, the direction of contact between the workpiece and the grindstone 3 changes from the center to the end of the processing curved surface 2 in the X-axis direction. That is, when the grindstone 3 is located at a position shown by a two-dot chain line in FIG. 9 with respect to the workpiece 1, the contact direction between the workpiece 1 and the grindstone 3 (contact point P3) is the cutting direction of the grindstone (Z axis direction). 9), the workpiece 1 and the grindstone 3 are maintained when the grindstone 3 reaches the position shown by the solid line in FIG.
The contact direction (contact point P4) is shifted by an angle θ2 from the normal 5 of the curved surface 2 which coincides with the direction of the grinding wheel cutting feed. As a result, a deviation corresponding to θ2 occurs between the processing position of the curved surface controlled by the NC shape data of the curved surface and the actually processed position, which has an adverse effect on the accuracy of generating the curved surface, and also causes wear of the grinding wheel. Then, the influence on the creation accuracy cannot be ignored, and it may not be possible to use the mold for the toroidal mirror. SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide a curved surface processing method capable of improving the accuracy of forming a curved surface shape of a workpiece while maintaining a constant contact direction between the workpiece and a grindstone. Aim. [0008] In order to achieve the above object, the present invention relates to a curved surface machining method for machining a three-dimensional free-form surface on a workpiece by using a grindstone, wherein the support portion supports the workpiece. A grindstone head having a disk-shaped grindstone that is rotationally driven; first driving means for relatively moving the support portion and the grindstone head in a cutting direction in which the workpiece and the grindstone are separated from each other; and the cutting direction. Second driving means for relatively moving the support portion and the grindstone head in a traverse feed direction perpendicular to the third direction, and third drive for relatively moving the support portion and the grindstone head in a pitch feed direction perpendicular to the traverse feed direction.
Driving means, and fourth driving means for swinging the support portion or the grindstone head around an axis parallel to the traverse feed direction, and the support portion or the grindstone head around an axis parallel to the pitch feed direction. A fifth drive unit for swinging, the third drive unit feeds the support portion and the grindstone head relatively in a pitch feed, and for each pitch feed feed, a normal line to a processing curved surface of the workpiece. A first step of swinging the support portion or the grinding wheel head by the fourth driving means so that a cutting direction of the grinding stone coincides with the first driving step; The first driving means moves the support unit and the grinding wheel head relative to each other to relatively cut the grinding wheel while moving the grinding wheel head and the grinding wheel head in the traverse feed direction. A second step of swinging the support portion or the grinding wheel head by the fifth driving means so that a normal line of a processing curved surface of the workpiece and a cutting direction of the grinding wheel coincide with each other, and By repeating the first step and the second step, a three-dimensional free-form surface is machined on the workpiece. In the present invention, each time the swing table and the grindstone head are relatively pitch-fed, the swing table is swung about an axis parallel to the traverse feed direction according to the curved surface shape data, and While relatively moving the swing table and the grindstone head in the traverse feed direction, the swing table and the grindstone head are relatively moved in the notch feed direction, and at the same time, the swing table is curved surface data around an axis parallel to the pitch feed feed direction. By swinging according to
Even if the normal of the free-form surface changes as the free-form surface is machined, the relationship between the normal of the free-form surface and the grinding wheel head can always be kept the same. Therefore, the accuracy of creating a workpiece curved surface can be improved. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partially cutaway front view of a five-axis control curved surface processing machine to which the method of the present invention is applied, and FIG. 2 is a left side view thereof. 1 and 2, reference numeral 10 denotes a bed installed on a floor 11 via a vibration isolator 12, and 13 denotes a bed 10.
The slide table 13 is mounted on a guide member 14 so as to be movable in the X-axis direction (traverse feed direction). The slide table 13 includes a ball screw 15 provided on the bed 10 side and a servo motor for rotating the ball screw 15. 16 is configured to be moved in the X-axis direction. Reference numeral 17 denotes a first swing table provided on the slide table 13. The first swing table 17 is supported by a support member 18 on the slide table 13 by a support shaft 18 parallel to the X-axis direction. 19 is supported so as to be swingable around the A axis. A first drive mechanism 20 that swings the first swing table 17 around the A axis is installed on the slide table 13 by a support member 21. The first drive mechanism 20 includes a ball screw 201 installed in a vertical direction, and a servomotor 202 for driving the ball screw 201 to rotate.
The first nut member 203 is connected to the first swing table 17. Reference numeral 22 denotes a second swing table supported on the first swing table 17 by a support shaft 23 so as to be able to swing around a B-axis orthogonal to the A-axis. The second drive mechanism 24 that swings the first arm about the B axis is supported on the first swing table 17 by a support member 25. The second drive mechanism 24 includes a ball screw 241 arranged vertically and a servomotor 242 for driving the ball screw 241 to rotate.
The first nut 243 is connected to the second swing table 22. Reference numeral 1 denotes a workpiece set on the second swing table 22. In FIG. 1 and FIG. 2, reference numeral 26 denotes a gate-shaped column fixed on the bed 10. A grindstone mount 27 is provided on a horizontal portion 26a of the column 26 by a guide portion 28 in the Y-axis direction (pitch feed feed). The grinding wheel base 27 is mounted on a column horizontal portion 26a in a Y-axis direction by a ball screw 29 disposed in parallel with the Y-axis direction and a servomotor 30 for rotating the ball screw 29. It is configured to be moved to. On the whetstone mount 27, an elevating member 31
A disc-shaped grinding wheel 32 whose grinding surface forms an arc and an electric motor 33 for rotating the grinding wheel 32 are integrated at the lower end of the elevating member 31 so as to be slidable in the axial direction (cut feed direction). A grindstone head 34 is mounted. The lifting member 31 is placed on the grindstone base 27.
A servo motor 35 is installed in opposition to the servo motor 35, and an upper end of the servo motor 35 is connected to an upper end of the elevating member 31 by a ball screw (not shown). The whetstone head 34 is moved in the Y-axis direction. Next, the configuration of a control unit to which the method of the present invention is applied will be described with reference to FIG. In FIG. 3, a numerical control device 40 that controls a processing machine with five axes includes a central processing unit (hereinafter abbreviated as CPU) 41 that controls and manages the entire processing machine.
Memory 42 for storing programs and data, CPU
The drive pulse is supplied to the X axis, Y axis, Z
A pulse distribution circuit 43 for distributing and supplying the servomotors for the axes A, B and A is provided. The pulse distribution circuit 43 includes servo motors 16 for driving the slide table (for the X-axis), a servomotor 30 for driving the grinding wheel gantry (for the Y-axis), and a grinding wheel feed through separate driving circuits 44 to 46. (For Z axis) Servo motor 35
Are connected respectively. Further, the pulse distribution circuit 4
The servomotor 202 for driving the first swing table (for the A-axis) and the servomotor 242 for driving the second swing table (for the B-axis) are separately provided via drive circuits 47 and 48 respectively.
Are connected respectively. As shown in FIG. 1, the memory 42 stores NC shape data (x, y, z, α, β) of a workpiece input from the input device 49, a machining program, and the like. In the configuration of the above embodiment, the servo motor 16 serves as the second drive means, the servo motor 30 serves as the third drive means, the servo motor 35 serves as the first drive means, and the first drive means serves as the first drive means.
Drive mechanism (servo motor 202) 20 is a fourth drive means, second drive mechanism (servo motor 242) 24 is a fifth drive means, and first and second swing tables are support portions, respectively. Constitute. Next, the curved surface machining operation of the embodiment configured as described above will be described. When the workpiece 1 is to be subjected to a curved surface processing, a drive command is given from the CPU 41 to the pulse distribution circuit 43 according to the machining program in the memory 42 and the NC shape data (x, y, z, α, β). The servo motor 16 is driven by the drive pulse sent from the oscillating tables 17 and 22.
The servo motor 30 is moved by the drive pulse from the pulse distribution circuit 43 based on the NC shape data and the machining program while moving the slide table 13 including the
To move the grindstone head 34 including the grindstone gantry 27 in the Z-axis direction, and at the same time, drive-control the servomotor 242 to swing the second swing table 22 around the B-axis. The workpiece 1 is subjected to one-pass machining in the X-axis direction. At this time, as shown in FIG. 4, the second swing table 22 is swung as the grindstone 32 with respect to the workpiece 1 is moved from the position shown by the solid line to the position shown by the two-dot chain line. Since the workpiece 1 is also swung about the B axis from the state shown by the solid line in FIG. 4 to the state shown by the two-dot chain line, the contact direction between the workpiece 1 and the grinding wheel 32 is in the grinding wheel cutting direction (Z axis direction). Will be maintained. Thus, the contact direction between the workpiece 1 and the grindstone 32 does not deviate from the cutting direction of the grindstone as in the related art, and can always be maintained in the same state. When the one-pass machining for the workpiece 1 is completed, the CPU is executed according to the machining program and the NC shape data.
By giving a drive command to the pulse distribution circuit 43 from 41, the servo motor 30 is driven by the drive pulse sent from the pulse distribution circuit 43, and the grindstone head 34 including the grindstone gantry 27 is moved by one pitch in the Y-axis direction. Further, the servo motor 202 is driven by a drive pulse sent from the pulse distribution circuit 43 based on the NC shape data to swing the first swing table 17 around the A axis by a predetermined angle. In this case, the Y of the grindstone 32 with respect to the workpiece 1
As the feed position of the pitch feed in the axial direction is moved from the position of the solid line to the position of the two-dot chain line as shown in FIG. 5, the workpiece 1 changes from the state shown by the solid line in FIG. Since the workpiece 1 is swung, the contact direction between the workpiece 1 and the grindstone 32 is maintained in the grindstone cutting direction (Z-axis direction). Thus, the contact direction between the workpiece 1 and the grindstone 32 does not deviate from the cutting direction of the grindstone as in the related art, and can always be maintained in the same state. After one pitch feed of the grindstone head 34 in the Y-axis direction is completed, the workpiece 1 is subjected to one-pass machining by performing X-, Z-, and B-axis control again. Hereinafter, by repeating the same operation, the entire surface of the workpiece 1 is processed into a curved surface according to the NC shape data. FIG. 6 schematically shows a state of the series of curved surface processing described above. In this embodiment as described above, while moving the workpiece 1 and the slide table 13 including the swing tables 17 and 22 in the X-axis direction, the whetstone head 34 including the whetstone mount 27 is moved in the Z-axis direction. Cut feed and at the same time the second
The swing table 22 is swung about the B axis to perform one-pass machining of the workpiece 1, and the grindstone head 34 is moved by one pitch in the Y axis direction, and the first swing table 17 is swung about the A axis. After swinging by a predetermined angle, the above-mentioned one-pass machining is performed again. Therefore, as shown in FIGS. 4 and 5, as shown in FIGS. Can be maintained in the normal direction. That is, the relationship between the normal F of the processing curved surface 2 at the point where the workpiece 1 contacts the grinding wheel 32 and the direction of the grinding wheel head 34 is always determined despite the change in the direction of the normal of the processing curved surface 2. Can be kept constant. Accordingly, the accuracy of creating the curved surface shape of the workpiece 1 is improved. In the embodiment described above, the swing table 1 is used.
The example in which the direction of contact between the workpiece 1 and the grindstone 32 is made to coincide with the direction of the grindstone head 34 by swinging the grindstones 7 and 22 around the A axis and the B axis has been described. Around the B axis,
The swing tables 17 and 22 may swing around the A axis, or vice versa. Further, the present invention is not limited to the configuration shown in the above embodiment, and various modifications can be made without departing from the scope described in claims. As described above, according to the present invention , a work piece
Has a supporting part to support and a disk-shaped grinding wheel that is driven to rotate
The grinding wheel head, the workpiece and the grinding wheel move toward and away from each other
Relatively move the support and the grinding head in the cutting direction
First driving means and a traverse perpendicular to the cutting direction
A step of relatively moving the support portion and the grinding wheel head in the feed direction
2 and a pit that is perpendicular to the traverse feed direction.
Relative to the support and the grinding head in the feed direction.
A third driving means for moving the support portion or the grindstone head.
Swing around an axis parallel to the traverse feed direction.
Fourth driving means, and the supporting portion or the grinding wheel head
Swing about an axis parallel to the pitch feed direction.
A fifth driving means, and the third driving means
Pitch feed relative to the support and the grinding head
And every time the pitch feed is fed,
In order to make the normal line and the cutting direction of the grinding stone coincide with each other,
The support unit or the grinding wheel head is swung by the driving means of 4.
A first step to perform, and a second drive after the first step
How to traverse the support and the grinding head by means
While being relatively moved in the direction
Move the support part and the grindstone head relatively to cut the grindstone.
At the same time as the feed
Make sure that the normal of the curved surface matches the cutting direction of the whetstone
The supporting portion or the grinding wheel head by the fifth driving means.
A second step of oscillating the gate, wherein the first step
Three-dimensional freedom on the workpiece by repeating the second step
It is characterized by processing a curved surface. Accordingly
According to the present invention , each time the workpiece support and the grindstone head are relatively pitch-fed, the support or the grindstone head is swung about an axis parallel to the traverse feed direction. Since the support portion and the grindstone head are relatively moved in the cutting feed direction while the head is relatively moved in the traverse feed direction, and at the same time the support portion or the grindstone head is swung about an axis parallel to the pitch feed feed direction,
Even if the normal of the free-form surface changes as the free-form surface of the workpiece changes, the relationship between the normal of the free-form surface and the grinding wheel head can always be kept constant. Accordingly, the contact direction between the workpiece and the grinding wheel can always be maintained in a state that matches the grindstone depth cutting direction, it is possible to improve the creation accuracy of curved shape of the Engineering crops.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cutaway front view of a processing machine to which the method of the present invention is applied. FIG. 2 is a left side view of FIG. FIG. 3 is a block diagram illustrating a configuration of a control unit according to the embodiment of the present invention. FIG. 4 is an explanatory diagram showing a contact relationship between a workpiece and a grindstone in the present embodiment. FIG. 5 is an explanatory diagram showing a contact relationship between a workpiece and a grindstone in the present embodiment. FIG. 6 is an explanatory diagram schematically showing a state of a curved surface processing in the present embodiment. FIG. 7 is an explanatory view showing a processing state of a conventional workpiece having a toroidal curved surface. FIG. 8 is an explanatory view showing a conventional contact relationship between a workpiece and a grindstone. FIG. 9 is an explanatory view showing a conventional contact relationship between a workpiece and a grindstone. DESCRIPTION OF SYMBOLS 13 Slide table 16 Servo motor (second drive means) 17 First swing table 20 First drive mechanism (Fourth drive means) 22 Second swing table 24 Second drive Mechanism (Fifth Driving Means) 30 Servo Motor (Third Driving Means) 32 Grinding Stone 33 Grinding Stone Head 35 Servo Motor (First Driving Means) 40 Numerical Controller

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-300152 (JP, A) JP-A-2-53557 (JP, A) JP-A-5-69300 (JP, A) 55946 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B24B 1/00 B24B 13/00

Claims (1)

(57) [Claim 1] A curved surface machining method for machining a three-dimensional free-form surface on a workpiece with a grindstone, comprising: a support portion for supporting the workpiece; A grindstone head having a grindstone, first driving means for relatively moving the support portion and the grindstone head in a cutting direction in which the workpiece and the grindstone come and go with each other, and the support in a traverse feed direction perpendicular to the cutting direction. Second driving means for relatively moving the portion and the grinding wheel head, third driving means for relatively moving the support portion and the grinding wheel head in a pitch feed direction perpendicular to the traverse feeding direction, and the support portion or the grinding wheel head A fourth driving means for swinging the shaft around an axis parallel to the traverse feed direction, and a fifth drive means for swinging the support portion or the grindstone head around an axis parallel to the pitch feed direction. A motion means, said third said support and the grinding wheel head feed relative pitch feed by the driving means, the cutting direction of the normal to the grinding wheel machining curved surface of the workpiece for each said pitch feed Feed
A first step of oscillating the support portion or the grinding wheel head by the fourth driving means so that the first and second driving means coincide with each other. While relatively moving in the traverse feed direction, the first drive means relatively moves the support portion and the grindstone head to give a cut to the grindstone, and at the same time, according to the cut feed position, the normal to the processing curved surface of the workpiece. switching of said grinding wheel
A second step of swinging the support portion or the grindstone head by the fifth driving means so that the setting direction coincides with the second driving step, and repeating the first step and the second step.
More three-dimensional free-form surfaces are machined on workpieces.
And a curved surface processing method characterized by the following .