JPH11347823A - Cutting method for metal mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cut a high-precision deep groove shape quickly at a low cost with end mill machining alone by keeping the direction and size of cutting resistance constant against the tool feeding direction when an end mill is reciprocated to cut the deep groove shape of a metal mold. SOLUTION: An end mill 1 is linearly moved in the longitudinal direction of the groove of a metal mold 2 in the plane perpendicular to the rotation axis. When the end section of the groove has an R-shape, the end mill 1 is moved to the face on the opposite side to the forward path while drawing a spiral tool locus and cuts the groove by the prescribed quantity in the rotation axis direction. On the return path, the end mill 1 is linearly moved in the opposite direction to the forward path. At the end section of the groove, the end mill 1 is moved to the face on the opposite side to the return path while drawing the spiral tool locus again and cuts the groove by the prescribed quantity. These actions are repeated to the prescribed depth to machine the groove. The machining allowance is quite equal for the forward path and the return path in the feeding direction of a tool, thus cutting resistance is equal for both paths. The cutting resistance during linear movement is constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cutting a die with an end mill.

[0002]

2. Description of the Related Art In the machining of a groove shape, cutting is usually performed using an end mill. In the cutting process having the shape shown in FIG. 1, it is necessary to use an end mill having a diameter equal to or smaller than the groove width and longer than the groove depth. As a method of cutting grooves and pockets using the end mill 1, for example, Japanese Patent Application Laid-Open Nos.
As described in Japanese Unexamined Patent Publication No. -150305, attempts have been made to improve machining efficiency and prevent cutting edge breakage of an end mill by devising a tool trajectory. However, an end mill having low bending rigidity was used. A method for improving the processing accuracy in such a case has not been studied.

[0003]

The smaller the diameter and the longer the tool length, the lower the bending rigidity of the end mill. In the grooving by the end mill, the cutting resistance acts on the cutting edge of the end mill during the cutting process. Therefore, the lower the bending rigidity, the more easily the end mill is elastically deformed, and the lower the machining accuracy. As shown in ()), processing accuracy defects such as bending, undulation, and deviation of grooves are likely to occur. as a result,
In addition to the deterioration of the shape accuracy of the molded product, problems such as deterioration of the releasability of the molded product occur. Therefore, electric discharge machining had to be used for machining the deep groove shape. In the electric discharge machining, not only the machining time is long, but also it is necessary to manufacture an electrode. Further, since the surface roughness is poor, manual polishing is required, and the manufacturing period of the mold is extremely long.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a drawback of the prior art. In the reciprocating processing of a groove, the direction of the cutting resistance with respect to the feed direction of the end mill is made constant, and the forward and backward paths are performed. The present invention provides a cutting method capable of preventing a deterioration in shape accuracy such as bending or deviation of a groove by equalizing a cutting resistance of a groove, and enabling a high-precision mold to be manufactured in a short period of time and at low cost. It is in.

[0005]

According to the present invention, 1 / one of the groove width is used.
Reciprocating processing is performed using an end mill having a diameter of 2 or more and smaller than the groove width. On the outward path, only one surface of the groove is cut by horizontal feed, and on the return path, a predetermined cut is made in the axial direction of the end mill. This is achieved by cutting the surface on the side opposite to the outward path.

[0006]

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

FIG. 3 is a diagram showing an outline of an embodiment of the method of the present invention. FIG. 3 shows a case of processing a blind groove.
The end mill 1 linearly moves in the longitudinal direction of the groove in a plane perpendicular to the rotation axis. If the groove end has an R shape, the groove is cut by a predetermined amount in the direction of the rotation axis while moving to the surface opposite to the outward path while drawing a spiral tool path.
In the return path, the groove moves linearly in the direction perpendicular to the rotation axis in the longitudinal direction of the groove in the direction opposite to the outward path. At the end of the groove, a predetermined amount is cut while moving to the surface opposite to the return path while drawing a spiral tool path again. By repeating this operation up to a predetermined groove depth, the groove can be processed.

In the method according to the present invention, as shown in FIG. 4, the clearances in the forward path and the return path are completely the same when viewed from the feed direction of the tool, so that the cutting forces are equal. Furthermore, during linear movement, the end mill 1 only moves in a plane perpendicular to the rotation axis 2, so that the cutting force during movement is constant.
Therefore, in the method of the present invention, the direction and magnitude of the elastic deformation of the end mill are always constant with respect to the feed direction of the end mill 1, and no bending or deviation of the groove occurs.

FIG. 4 shows the cutting force in the method of the present invention. For comparison, the cutting force in the conventional method is also shown. The graph of the cutting resistance in FIG. 4 is obtained when the grooving is performed with the work material placed on the cutting dynamometer. The cutting resistance in the present processing method is opposite in direction and equal in magnitude in the forward path and the return path.

On the other hand, in the inclined cutting which is a conventional method, since the cutting is performed in the axial direction of the end mill during the linear movement, the magnitude of the cutting resistance gradually increases during the linear movement. Also, in contour processing, the magnitude of the cutting resistance in the outward path and the return path is different.

FIGS. 5A and 5B schematically show the magnitude and direction of the cutting force in each of the processing methods shown in FIGS.
FIG. 6 to FIG. 6 schematically show the contours of the grooves in each processing method of FIG. In the processing method of the present invention, only the contour of the groove is uniformly increased with respect to the predetermined shape,
No bending or biasing occurs. However, in the case of inclined cutting, which is a conventional processing method, bending of a groove occurs. Further, in contour processing, deviation of grooves occurs.

Although the embodiment of the present invention has been described using an example of processing of a stop groove, the processing method of the present invention can be applied to a groove having an open end or a straight groove having an end. . Although the embodiment of the present invention has been described using an example in which a ball end mill is used, the processing method of the present invention can be similarly applied to a case where a square end mill is used.
In the method of the present invention, when the groove width does not reach the predetermined dimension, the groove width can be adjusted to the predetermined dimension by correcting the tool path.

[0013]

According to the present invention, in the machining of a deep groove shape, bending or deviation occurs, and conventionally, electric discharge machining had to be used.
Therefore, the processing time is long, and a polishing step is required to improve the surface roughness. However, according to the processing method of the present invention, a deep groove shape can be processed with high precision only by end milling, so that processing can be performed in a short time, and since the surface roughness is good, a polishing step is not required, and a mold can be manufactured in a short time and at low cost. There is an effect that can be manufactured.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a conventional deep groove end milling.

2 (a) and 2 (b) are perspective views schematically showing problems in a conventional deep groove end milling.

FIG. 3 is a perspective view showing an end mill processing according to the embodiment of the present invention.

FIG. 4 is a perspective view showing a margin in the deep groove machining method of the present invention.

FIG. 5 is a perspective view showing waveforms of cutting resistance in the deep groove machining method of the present invention and the conventional method.

FIG. 6 is a perspective view schematically showing directions and magnitudes of cutting forces in the deep groove machining method of the present invention and a conventional method.

[Explanation of symbols]

 1. End mill, 2. Mold.

Claims (1)

[Claims] 1. A method for machining a groove with high precision by making the direction and magnitude of a cutting resistance constant in a tool feeding direction in machining a deep groove of a mold by reciprocating movement of an end mill.