JP3085339B2 - Machining method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machining method, and more particularly to a machining method using an NC machine tool having a rotary feed shaft.
The present invention relates to a machining method for performing continuous machining while avoiding interference between a workpiece and a tool system in grinding.

[0002]

2. Description of the Related Art In the processing of a workpiece having a curved surface, triaxial processing is mainly performed using a ball end mill or a grinding wheel with a shaft having a spherical tip. When performing axis machining, interference occurs between the workpiece and the tool gripping portion. In order to avoid this interference, lengthen the protruding length of the tool or change the mounting position of the work, for example,
By rotating the A-axis and the B-axis of the axis machine tool, the workpiece is indexed several times in an easy-to-machine direction, and the relative posture between the workpiece and the tool grip is changed to perform the machining.

[0003]

FIG. 7 is an explanatory view of a conventional three-axis machining method. In the three-axis machining, a ball end mill 71 is used as a tool, and a tool holder 72 or a tool holder for holding the ball end mill 71 is used. 7 shows a state in which a main shaft 73 that grips 72 interferes with a work 74 in an interference area 75. To avoid this interference, the tool length should be increased from l1 to l2. However, if the tool length is increased, the position of the tip of the tool is shifted during machining, thereby reducing machining accuracy. Since the vibration disappears and chatter vibration occurs, there is a problem that the cutting feed speed must be reduced and the machining efficiency is reduced.

FIG. 8 is an explanatory view of a five-axis interrupted machining method according to the prior art. When a tool holder 82 for holding a ball end mill 81 or a main shaft 83 for holding the tool holder 82 interferes with a work 84 in an interference area 85. An example in which the work 84 is rotated clockwise by θ ° around the A-axis or the B-axis in five-axis machining to avoid the interference will be described. In this case, the rotation angle is intermittently indexed several times in a direction in which the workpiece can be easily processed, and the X-axis, Y-axis, and Z-axis processing are performed by setting the A-axis and the B-axis at a predetermined angle. There is a problem that the setup requires time and labor. In addition, since the workpiece is machined by indexing several times, a step of several microns occurs between the machining surfaces machined in different indexing postures,
There is a problem that the machined surface is not smooth, and it takes time and effort to work the workpiece surface in the finishing process. In order to solve this problem, it is conceivable to perform surface processing continuously.

Accordingly, it is an object of the present invention to provide a machining method which does not have the above-mentioned problems, that is, performs continuous machining while avoiding interference between a workpiece and a tool gripping portion.

[0006]

FIG. 1 is a flow chart showing the basic processing of a machining method according to the present invention. In order to achieve the above object, the machining method according to the present invention comprises three linear feed axes orthogonal to each other, that is, an X axis, a Y axis, and a Z axis;
At least one of the B-axis rotating around the Y-axis or the Y-axis is mounted on the rotary spindle of the NC machine using a tool having an arcuate cutting edge at the tip. In the machining method for machining a workpiece by using the method, the method includes the following steps.

(First stage) Work shape data as data representing the shape of a work to be processed is stored. (Second stage) The shape data of the conical interference model obtained by connecting the tool center point at the tip of the tool and the tool holder for holding the tool or the outermost portion of the main spindle for holding the tool holder is stored. (Third step) While feeding the tool according to the tool path specified in advance, it is determined whether or not the workpiece and the conical interference model interfere with each other based on the workpiece shape data and the conical interference model, and the result of the determination is made. If it is determined that there is no interference, the machining is continued as it is, and if it is determined that there is interference, the relative position between the workpiece and the tool is adjusted to rotate the A-axis or B-axis rotary feed shaft to avoid the interference. Change the posture and continue processing to perform continuous processing.

[0008]

FIG. 2 is a block diagram of the control means of the present invention.
A control unit 21 comprising a CPU for controlling the whole, a work shape data storage unit 22 for storing work shape data, a cone shape interference model data storage unit 23 for storing cone shape interference model data described later, A machining program storage unit 24 that stores a machining program mainly including a moving path of the tool, and an A that drives an A axis that is a rotation axis around the X axis and a B axis that is a rotation axis around the Y axis of the 5-axis NC machine tool 26. , B-axis drive unit 25.

The control unit 21 stores the work shape data storage unit 2
2 at the position of the tool along the path of the tool from the workpiece shape data stored in the tool 2 and the shape data of the cone shape interference model stored in the cone shape interference model data storage unit 23. Work to be processed with
Determine whether or not there is interference with the conical interference model that approximates the shape around the tool, and when it is determined that there is no interference, move the tool along the tool path as it is to continue machining, When it is determined that there is interference, a rotation amount for rotating the A-axis or the B-axis is calculated so as to avoid the interference, and the A- and B-axis driving units 25 are controlled to control the 5-axis NC machine tool 2.
The control is performed so that the A axis and the B axis of No. 6 are rotated by a predetermined angle, and the tool is moved along the tool path to continue the machining.

According to the machining method of the present invention, since the interference between the work and the tool gripping portion is checked and the relative posture of the work and the tool is controlled so that they do not interfere, the continuous machining is performed. High-precision high-speed machining can be realized.

[0011]

FIG. 3 is an explanatory view of a 5-axis continuous machining method according to the present invention. The figure shows a tool holder 32 for holding the ball end mill 31 or a spindle 33 for holding the tool holder 32.
An example is shown in which the tool axis is rotated counterclockwise by θ ° with the center point 36 of the tool as a fulcrum in order to avoid the interference when the tool interferes with the work 34 in the interference area 35. In this case, X, while continuously performing this rotation angle control,
Since the three-axis machining of Y and Z is performed, the problem of the prior art is solved,
That is, it is possible to maintain the processing accuracy, improve the processing efficiency, and further reduce the time and labor required for setup. The same is true if the work is inclined instead of the tool.

FIG. 4 is an explanatory diagram of the milling roughing process. A procedure for roughing the workpiece 44 by the milling cutter 41 will be described below. This figure shows a sectional view of the work 44 and the milling cutter 41 immediately before processing. The cross section of the material shape of the work 44 is a rectangle surrounded by points L1, L2, L3, and L4, and the cross-sectional shape of the product after final processing is a shape surrounded by points L41, L42, L3, and L4. A curve between the points L42 is a curve. When performing such a process, first, a milling roughing process is performed.

It is clear from the figure that in this rough milling, it is preferable to perform the above-mentioned indexing three times using a 5-axis NC machine tool. After the first indexing, that is, after setting the A-axis and the B-axis at a predetermined angle, the milling roughing is performed from the linear processing between L1 and L2 to L1.
1. Straight line processing is performed several times from right to left in the figure until straight line processing between L12. Similarly, after the second indexing, the milling roughing is performed from the linear machining between L21 and L22 to L23 and L2.
The straight line machining is performed several times from the lower left to the upper right in the figure several times until the straight line machining between four. Similarly, after the third indexing, the milling roughing is performed by straight-line machining from the lower right to the upper left in the figure several times from the linear machining between L31 and L32 to the linear machining between L33 and L34.

FIG. 5 is an explanatory view of a conical interference model according to the present invention. This drawing is a cross-sectional view when a tool 51 such as a ball end mill, a tool holder 52 for holding the tool 51, and a tool gripping portion including a spindle 53 for holding the tool holder 52 move on the curved surface of the work to process the work. Show. The conical interference model of the present invention is a tool which is a point which is directed from the foremost point 57 of the tool 51 having an arc-shaped cutting edge to the main axis 53 along the tool center axis by an arc radius R formed by the tool tip. The center point 56 is obtained by connecting the tool holder 52 and the outermost portions of the main shaft 53, M1 and M2 in this case. The conical shape interference model data is data representing the shape of the conical shape interference model. This data is stored in the storage unit of the control means, and the data is used for checking the interference between the workpiece and the tool gripping unit. The curve P ₁ P ₂ representing one curved surface of the workpiece is subdivided, and at each of the subdivided points, the tool posture is controlled while performing an interference check.

FIG. 6 is an explanatory view of a working example according to the present invention. This figure shows the cross section when the tool gripper moves on the curved surface of the workpiece and the workpiece is machined. In the machining using a 5-axis machine tool, the workpiece shape after roughing and the conical interference model of the tool are shown. One XZ plane orthogonal to the Y axis is shown to determine the amount of rotation change around the Y axis that does not interfere. In this drawing, the workpiece shape after the roughing is shown by a solid line, the movement locus (tool path) of the tool center point during the workpiece surface processing is shown by an alternate long and short dash line, and the final machining shape of the workpiece is shown by an alternate long and two short dashes line. The tool center point of each tool during workpiece machining is A, B, C,
The shapes of the respective conical interference models at the positions D and E are indicated by dotted lines. The ball end mill 61 is gripped by a tool holder 62, and the tool holder 62 is
Is gripped by

By analyzing FIG. 6, it is possible to obtain a rotation change amount around the Y-axis where the workpiece shape after roughing does not interfere with the conical interference model as described below. While controlling the X, Y, and Z axes of the 5-axis machine tool to move the tool, A is a rotation axis around the X axis so that the conical interference model does not interfere with the workpiece shape after roughing. Continuous machining is performed by controlling the rotation of the B-axis, which is a rotation axis about the axis and the Y-axis. In this embodiment, when the center point of each tool during the machining of the workpiece is at the position of A, C, or E, the posture of the tool is vertical. That is, the tool axis is parallel to the Z axis, and interference can be avoided. When the tool center point during workpiece machining is at position B,
The orientation of the tool can be avoided by rotating the B axis clockwise by θ1 around the Y axis, that is, by setting the axis rotated clockwise by θ1 around the Z axis as the tool axis. When the center point of the tool during workpiece machining is at the position D, the posture of the tool is rotated by rotating the B axis counterclockwise around the Y axis by θ2, ie, rotating the Z axis counterclockwise by θ2 around the Y axis. If the set axis is used as a tool axis, interference can be avoided. In this figure, only the rotation change amount around the Y axis is shown, but similarly, the rotation change amount around the X axis is Y axis orthogonal to the X axis.
Since the analysis may be performed on the Z plane, the description is omitted.

[0017]

As described above, according to the machining method of the present invention, the rotation angle of the A-axis and the B-axis can be adjusted along the tool moving path in the five-axis machine tool while the tool length is short. Since continuous machining can be performed while rotating so as to avoid interference with the system, high-speed and high-accuracy machining can be realized.

[Brief description of the drawings]

FIG. 1 is a flowchart of basic processing steps of a machining method according to the present invention.

FIG. 2 is a block diagram of control means of the present invention.

FIG. 3 is an explanatory diagram of a 5-axis continuous machining method according to the present invention.

FIG. 4 is an explanatory diagram of a milling roughing process.

FIG. 5 is an explanatory diagram of a conical interference model of the present invention.

FIG. 6 is an explanatory view of a working example according to the present invention.

FIG. 7 is an explanatory view of a conventional three-axis machining method.

FIG. 8 is an explanatory view of a conventional 5-axis machining method.

[Explanation of symbols]

 31, 61, 71, 81 ... ball end mill 32, 62, 72, 82 ... tool holder 33, 63, 73, 83 ... spindle 34, 44, 64, 74, 84 ... work 35, 75, 85 ... interference area 36, 56, 66: Tool center point 41: Milling cutter

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-8148 (JP, A) JP-A-3-103902 (JP, A) JP-A-1-205956 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B23Q 15/00-15/28 G05B 19/18-19/46

Claims (1)

(57) [Claims] At least one of three linear feed axes orthogonal to each other, X-axis, Y-axis, and Z-axis, and at least one of an A-axis rotating around the X-axis and a B-axis rotating around the Y-axis. In a machining method for machining a workpiece by using a NC machine tool having an axis and mounting a tool having an arc-shaped cutting edge at a tip on a rotary spindle of the NC machine tool, the data as data representing the shape of the workpiece to be machined is provided. A first step of storing workpiece shape data; a cone-shaped interference obtained by connecting a tool center point at a tip portion of the tool and a tool holder for holding the tool or an outermost portion of a main spindle for holding the tool holder. A second step of storing the shape data of the model; and, while feeding the tool according to a tool path instructed in advance, the work and the cone from the work shape data and the shape data of the cone shape interference model. It is determined whether or not there is interference with the shape interference model. If the result of the determination is that there is no interference, the machining is continued as it is. If the result of the determination is that there is interference, the rotary feed shaft is used. A third step of changing the relative posture between the workpiece and the tool so as to avoid the interference by rotating the workpiece and continuing the machining.