JP2008110458A - Manufacturing method of end mill having circular arc blade - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate generation of fine difference in level and biting, etc. in a joint of flanks with each other of an outer peripheral cutting edge and a circular cutting edge of an end mill. <P>SOLUTION: In this manufacturing method, the outer peripheral cutting edge and the flank of the circular cutting edge of the end mill are continuously machined by the same grinding tool. In a first process, a workpiece is inclined to a grinding wheel rotary axis at a crossing angle A with a turning axis as a center, and the flank of the outer peripheral cutting edge is machined by linearly moving the workpiece in a workpiece rotary axis direction relatively to the grinding wheel by moving of the workpiece. In a second process, the flank of the circular cutting edge is machined by circular arc moving of the workpiece based on the circular cutting edge on the same plane as that in the linear moving relatively to the grinding wheel. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an end mill having an arcuate cutting edge such as a ball end mill or a radius end mill.

In Patent Document 1, after the outer peripheral flank 1 of the outer peripheral cutting edge 6 is first processed, the balls are continuously cut by the same flank machining program within the same NC machining program with the same grindstone (not shown). By machining the ball flank 2 of the blade 4, a step is eliminated between the outer peripheral flank 1 and the ball flank 2.
JP 2005-96044 A

  The problem of the present invention is that when shifting from the outer peripheral blade flank face of the end mill to the machining of the arc blade flank face, the plurality of axes used on the arc flank flank face is different from the plurality of axes used on the outer peripheral blade flank face. Therefore, due to the movement of the stopped shaft and the followability of the machine control, the movement of the grindstone is disturbed, resulting in minute steps or biting at the joint between the flank faces of the outer peripheral edge and arcuate edge of the end mill. There is a problem, and it is an issue to solve it.

  The present invention solves the above-mentioned problem, and in the manufacturing method of continuously processing the outer peripheral cutting edge of the end mill and the flank face of the arc blade with the same grindstone, as a first step, the workpiece is centered on the pivot axis. Inclining at a crossing angle A with respect to the grindstone rotation axis, and by moving the workpiece, linearly moving in the direction of the workpiece rotation axis relative to the grindstone to perform flank machining of the outer peripheral blade. A method of manufacturing an end mill having an arc blade, characterized in that the flank machining of the arc blade is performed by arcuate movement based on the arc blade on the same plane as the linear movement relative to the grindstone. is there. By applying the present invention, it is possible to manufacture a seamless end mill from the flank face of the outer peripheral blade to the flank face of the arcuate blade without the biting of the grindstone caused by the operation of the grinding machine.

  According to the present invention, it has been possible to provide a manufacturing method capable of obtaining an end mill having a circular arc blade such as a ball end mill or a radius end mill, which eliminates the biting of the grindstone into the joint portion and has no joint.

  As an example of the NC grinder used in the present invention, as shown in FIG. 1, the workpiece 1 is held by a chuck 2 so as to be rotatable about the workpiece rotation axis of the workpiece 1, and the chuck 2 is loaded on a table 3. 3 is mounted on a swivel base 4 and is rotatable about a swivel axis 5 of the swivel base 4. The grindstone 6 is mounted on a spindle 7 so as to be rotatable about a grindstone rotation axis. The spindle 7 can move in three directions of X axis, Y axis, and Z axis.

In FIG. 3, the first step of the present invention is that the workpiece 1 is tilted at a crossing angle A with respect to the grindstone rotation axis around the turning axis 5 and the X axis and Y axis are moved from the S point to the F point of the workpiece 1. By movement, the flank machining of the outer peripheral blade is performed by linearly moving in the direction of the workpiece rotation axis relative to the grindstone 6. In FIG. 3, the tip of the work 1 is hemispherical for convenience.
In the second step, when the first step reaches the point F, the movement amount of the X axis and the Y axis is changed from FIG. 4 to move the work 1 in an arc shape according to the arc radius of the rotation trajectory of the arc blade. Machining the flank face of the arc blade while
When moving from the first step to the second step, since the workpiece 1 is preliminarily inclined at the crossing angle A with respect to the grindstone 6, the peripheral surface 8 of the grindstone 6 interferes with the outer peripheral blade flank or arcuate blade flank after machining. This can be suppressed. The axis used for the movement in the first step and the axis used for the movement in the second step are the same axis, and it can be performed simply by changing the amount of movement of the shaft. It is possible to suppress the workpiece 1 from being tilted more than the NC command with respect to the grindstone 6 due to looseness based on the fitting error and the like, and the grindstone 6 biting into the flank of the outer peripheral blade or the arc blade.

  The crossing angle A is preferably set to 1 degree or more and 20 degrees or less, and when the workpiece 1 moves from the linear movement in the first process to the arc-shaped movement in the second process, the grindstone 6 becomes the flank of the outer peripheral blade. Interference can be suppressed, and the connecting portion between the flank faces of the outer peripheral blade and the arc blade can be provided smoothly. If the crossing angle A is less than 1 degree, the posture of the grindstone 6 with respect to the workpiece 1 during linear movement in the first step and the posture of the grindstone 6 with respect to the workpiece 1 in the second step do not change. The end face of the grindstone 6 interferes with the workpiece 1. It is important to adjust the crossing angle A to an appropriate angle depending on the outer diameter of the work 1. When the outer diameter is small, the crossing angle A is set to 10 to 20 degrees, and 1 to 10 as the outer diameter increases. Set to degrees. If the crossing angle A exceeds 20 °, the machining wheel shape must be an acute angle, so that the R accuracy due to grinding wheel wear during running processing may become unstable.

  Further, the second step is performed halfway along the arc blade, and then the workpiece 1 is swung using the swivel shaft 5 so that the swivel shaft 5 coincides with the center of the rotation trajectory of the arc blade when viewed from above. It is preferable to perform a turning process that processes the flank. Thereby, since the arc flank flank on the end mill tip side can be machined by the peripheral surface 8 of the grindstone 6, it becomes easy to give a desired flank angle to the tip side of the arc knives, and the design freedom of the end mill is increased. On the other hand, when the arc blade is machined only by the second process, the flank face of the arc blade located on the tip side of the end mill is machined by the side surface 9 of the grindstone 6, the grinding speed is slow, and the grinding heat of the spindle 7 Good grinding may not be possible due to the effect of elongation or the like. Here, the section length for performing the second step is preferably provided in an amount corresponding to the crossing angle A in the circumferential direction of the arcuate blade, so that when moving from the second step to the turning process, The arcuate blade can be machined on the peripheral surface, and the flank can be ground well. The relationship between the crossing angle A and the section length of the second process is obtained by the formula of section length of the second process = R × tan θ, where R is the radius of the circular arc blade. When the section length of the second step is long, the inclination of the rotation axis of the grindstone 6 with respect to the arc blade to be processed increases in top view, and the arc blade flank is processed on the side surface of the grindstone 6. The ground surface is easily roughened. Even when the workpiece 1 starts to move around the pivot axis 5 when moving from the second step to the turning process, the play only changes the position where the workpiece 1 and the grindstone 6 are in contact with each other by a minute angle. 6 can be prevented from interfering with the flank of the arcuate blade, and the flank of the arcuate blade can be provided smoothly without any step or bite. Hereinafter, the present invention will be described based on examples.

(Example 1)
Using the NC grinder described above, the outer peripheral blade flank and the ball blade flank of a ball end mill with two blades and a blade diameter of 10 mm were processed. As a grindstone used for processing, a flat grindstone having a grindstone diameter of 150 mm and a grindstone thickness of 2 mm was used.
As Example 1 of the present invention, a workpiece 1 that has been processed with a groove groove of a ball end mill is prepared, the workpiece 1 is held by a chuck 2, the crossing angle A in the first step is set to 1 degree, and the flank of the outer peripheral blade Next, the flank face of the ball blade was processed to the tip end side of the ball blade in the second step.
Comparative Example 2 is similar to Example 1 of the present invention in that the first step is performed, and the second step is a method of continuously machining the ball blade flank by turning the workpiece 1 using the turning shaft 5, respectively. Ten ball end mills were processed.

  As a result of observing the outer peripheral blade flank and ball blade flank state of Example 1 and Comparative Example 2 with an optical microscope 50 times, Example 1 of the present invention is shown in FIG. I couldn't see the bite at the seam. Stable machining was achieved with a radius accuracy of the ball blade rotation locus within 5 μm of the ideal radius. In Comparative Example 2, as shown in FIG. 7, biting occurred in 8 of 10 joints between the flank face of the outer peripheral blade and the flank face of the ball blade.

(Example 2)
As Example 3 of the present invention, in the same manner as Example 1 of the present invention, the position of the work 1 is adjusted in advance so that the center of the rotation locus of the ball blade to be processed and the turning shaft 5 coincide with each other in top view. The process is performed, and from the point F, the section length of the second process is machined by 0.17 mm in the circumferential direction of the ball blade, and then changed to the turning process, and the workpiece 1 is continuously centered around the turning axis 5. The remaining flank was machined by turning.
As a result, Example 3 of the present invention has no step at the joint between the flank face of the outer peripheral blade and the flank face of the ball blade, and further, there is no step on the flank surface of the ball blade, and good processing can be performed. The radius accuracy of the rotation trajectory was able to be processed within 3 μm from the ideal radius.

FIG. 1 shows a front view of a grinding machine. FIG. 2 shows a top view of FIG. FIG. 3 shows an outline of the first step. FIG. 4 shows an outline of the second step. FIG. 5 shows an example in which a part of the second step is turned. FIG. 6 shows the flank face of Example 1 of the present invention. FIG. 7 shows the flank face of Comparative Example 2.

Explanation of symbols

1: Work 2: Chuck 3: Table 4: Swivel table 5: Swivel axis 6: Grinding wheel 7: Spindle 8: Grinding wheel circumferential surface 9: Side surface of the grinding wheel A: Crossing angle between the grinding wheel rotation axis and the workpiece rotation axis S: No. Start point of one process F: End point of second process

Claims (3)

In the manufacturing method in which the outer peripheral cutting edge of the end mill and the flank face of the arc blade are continuously processed with the same grindstone, as a first step, the workpiece is tilted at a crossing angle A with respect to the grindstone rotation axis about the turning axis, Due to the movement of the workpiece, the flank machining of the outer peripheral blade is performed by linearly moving the workpiece in the direction of the workpiece rotation axis relative to the grindstone, and the second step is the linear movement relative to the grindstone. An end mill manufacturing method having an arc blade, characterized in that the flank machining of the arc blade is performed on the same plane by an arcuate movement based on the arc blade. The method for manufacturing an end mill having an arc blade according to claim 1, wherein the crossing angle in the first step is set to 1 to 20 degrees. The end mill manufacturing method having an arc blade according to claim 1, wherein a part of the second step is swiveled using a swivel shaft.