JP2009202258A - Method and apparatus for finishing curved surface shape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive method and an apparatus for finishing a curved surface shape providing a finished surface having a high surface roughness in an efficient reciprocating mode having a short machining time. <P>SOLUTION: In the finishing method for finishing a workpiece surface of a shape including a three-dimensional curved surface along a plurality of machining loci made at equal intervals along the shape by using a ball end mill B.E., an up-cut machining path machined next to a machining path subjected to down-cut is previously machined when the plurality of machining loci are machined in the reciprocating mode for machining by alternately changing their machining direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a curved surface finishing method and apparatus for finishing a workpiece surface including a three-dimensional curved surface using a rotary tool such as an end mill.

  In general, when finishing a workpiece surface that includes a three-dimensional curved surface such as a mold or aircraft part, a ball end mill is used to mark the shape surface with a plurality of equally-spaced machining trajectories. Without cutting. As shown in FIG. 5, the ball end mill B.B is a machining mode that defines the movement mode (machining path) of the ball end mill. E includes a one-direction (machining) mode (in the case of FIG. 5A) in which a plurality of machining trajectories are machined in the same direction, a reciprocating (machining) mode (FIG. 5B) in which the machining direction is changed alternately.

  In the unidirectional mode, the cutting condition of each machining locus is constant, so a uniform machining surface can be obtained. However, it is necessary to return to the starting point of the next machining locus each time machining of each machining locus is finished. , Ball end mill B. E has a feature that a great amount of machining time is required because it must move a distance of about twice the machining locus.

  On the other hand, in the reciprocating mode, the cutting conditions of the machining locus change alternately and the machining surface does not become uniform, but when the machining of each machining locus is finished, it is possible to move to the next machining locus with the shortest distance. B. It has the feature that the movement of E is small and efficient processing is possible.

  As can be seen from FIG. 5, since the cutting conditions are constant in the unidirectional mode, the processing trace remaining on the finished surface has a constant height (see FIG. 5A). The surface roughness is low because the widths of the two are different and do not become a constant height (see FIG. 5B).

  By the way, the difference in the cutting conditions in the reciprocating mode is the difference between the upcut (upward cutting; in the case of FIG. 4A) and the downcut (downward cutting: in the case of FIG. 4B) shown in FIG. FIG. 4 depicts the state of machining in the direction of looking at the tip from the source of the tool, and shows that the cutting force is broken down into feed force and back force. When machining with the same machining width, the ball end mill B. Since E is tilted in the direction perpendicular to the tool path by the back component force, the width of the machining trace is reduced, and in the up cut, the back component force is reduced in the opposite direction to the down cut. E is tilted in the direction of the cutting force, but has little effect on the width of the machining trace.

JP-A-8-292808

  As described above, conventionally, when finishing a curved surface shape with a ball end mill, in order to increase the surface roughness of the finished surface, the processing is not performed in a highly efficient reciprocating mode, but in a low efficiency one-way mode. This processing was necessary.

  In Patent Document 1, the tool radius r of the ball end mill used in the input / setting unit, the number of blades n, and the number of blades are used so that the surface of the workpiece having a three-dimensional curved surface can be processed efficiently and with high quality by a ball end mill. The rotational speed N, the height h of the cusp formed on the work, the work shape and work mode of the work, etc. are input, and the feed amount f per tooth is calculated from the input r and h by the f / p calculation unit. Further, the pick feed amount p is set equal to f. A tool path generating unit generates a tool path data from the p, the input machining shape and machining mode, and sends the tool path data to an NC device to perform cutting with a machine tool.

  However, Patent Document 1 does not describe anything about the one-way mode and the reciprocating mode.

  The present invention has been made in view of the above-described situation, and an object thereof is to provide a curved surface finishing method and apparatus capable of obtaining a finished surface with high surface roughness in an efficient reciprocating mode with a short machining time. And

  In order to achieve such an object, a curved surface finishing method according to the present invention uses a rotating tool to form a workpiece surface including a three-dimensional curved surface with a plurality of machining trajectories created at equal intervals along the shape. In the finishing method for finishing machining, when machining the plurality of machining trajectories in a reciprocating mode in which the machining directions are alternately changed, an up-cut machining path to be machined next to a machining path to be down-cut is preceded. And processing.

  Further, the rotary tool is an end mill.

  In order to achieve such an object, a curved surface finishing apparatus according to the present invention comprises an NC machine tool for finishing a workpiece surface by mounting a rotary tool on a spindle and moving relative to the workpiece. When finishing a workpiece surface having a shape including a three-dimensional curved surface having tool path data having a reciprocating mode for finishing machining in the order of machining paths described in Item 1, the machining described in Claim 1 A reciprocating mode in which finishing is performed in the order of the paths is sent to the NC machine tool for finishing.

  Further, the rotary tool is an end mill.

  According to the curved surface finishing processing method and apparatus according to the present invention, the upcut processing path for processing the upcut and the downcut processed alternately in the reciprocating mode is processed next to the processing path to be downcut. By machining first, down-cut cutting resistance that shifts the machining position due to large back force can be reduced, and machining deviation can be reduced, so surface can be cut in efficient reciprocating mode with short machining time A finished surface with high roughness can be obtained. In addition, since a simple means of changing the order of the processing paths in the reciprocating mode is sufficient, there is an advantage that the cost can be reduced.

  Hereinafter, a curved surface finishing method and apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram of a machining path showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of the order of machining traces and machining paths, and FIG. 3 is a block diagram.

  As shown in FIG. 3, the NC program automatically programmed by the CAD / CAM system 10 (including the one-way mode (refer to FIG. 5A), the normal reciprocal mode (refer to FIG. 5B), and the reciprocal operation of the embodiment described later. When a workpiece surface having a shape including a three-dimensional curved surface is finished by a command code of the NC device 11, the reciprocation of this embodiment is performed. Ball end mill B. A machine tool 12 having E mounted on the spindle is operated.

  As shown in FIGS. 1 and 2, the reciprocating mode of the present embodiment is a down-cut when machining a plurality of machining trajectories created at equal intervals along the shape of the workpiece surface by alternately changing the machining direction. (See FIG. 4B) The processing path of the upcut (see FIG. 4A) to be processed next to the processing path to be processed is processed in advance.

  That is, in the example of FIG. 2, the ball end mill B. is in the order of U (up cut) 1 → D (down cut) 1 → U 2 → D 2 → U 3 → D 3. E is reciprocated and processed.

  In other words, the machining path of the upcut is machined before machining with the machining path of the downcut, the part to be machined by the machining of the downcut is machined in advance, and the cutting resistance generated by the downcut is suppressed to a low level. Ball end mill B. This prevents the E tool path from falling in the direction perpendicular to it.

  In this way, in this embodiment, it is possible to reduce the cutting resistance of the down-cut that shifts the processing position due to a large back component force, and to reduce the processing deviation. A finishing surface having a high surface roughness can be obtained (see a downcut processing trace when processing is performed in a normal reciprocating mode (see FIG. 5B) indicated by a broken line in FIG. 2).

  In addition, in this embodiment, since simple means of changing the order of the processing paths in the reciprocating mode is sufficient, there is an advantage that an advanced control device or the like is not necessary and the cost can be reduced.

  In addition, this invention is not limited to the said Example, In the range which does not deviate from the summary of this invention, ball end mill B.I. It goes without saying that various changes such as using a corner R end mill in which the corner portion of the cutting edge is R processed instead of E are possible.

It is a schematic diagram of the processing path which shows one Example of this invention. It is explanatory drawing of the order of a process trace and a process path. It is a block diagram. It is explanatory drawing of the cutting conditions in reciprocating mode. It is explanatory drawing of a process mode.

Explanation of symbols

B. E Ball end mill D1, D2, D3 Machining path to be cut down U1, U2, U3 Machining path to be upcut 10 CAD / CAM system 11 NC unit 12 Machine tool

Claims (4)

  In a finishing method that uses a rotary tool to finish a workpiece surface including a three-dimensional curved surface with a plurality of processing trajectories created at equal intervals along the shape, the processing directions of the plurality of processing trajectories are alternately changed. A curved surface finish processing method, wherein when processing is performed in a reciprocating mode in which processing is changed, an up-cut processing path to be processed next to a processing path to be down-cut is processed in advance.   The curved surface finishing method according to claim 1, wherein the rotary tool is an end mill.   An NC machine tool that finishes a workpiece surface by mounting a rotary tool on a spindle and moving relative to the workpiece, and tool path data having a reciprocating mode for finishing in the order of the machining paths according to claim 1. When a workpiece surface having a shape including a three-dimensional curved surface is finished, a reciprocating mode for finishing in the order of the machining paths described in claim 1 is sent to the NC machine tool for finishing. A finishing apparatus with a curved surface, characterized in that:   4. The curved surface finishing apparatus according to claim 3, wherein the rotary tool is an end mill.

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