JP2017159389A - Drilling method using end mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately drill a hole in the entire depth of a hole by an end mill. SOLUTION: An end mill 1 having an outer diameter smaller than a target inner diameter of a target hole shape is prepared, helical interpolation is applied using the end mill 1, and a predetermined first diameter residual allowance L1 is left to reach a predetermined depth. After processing, with the first diameter remaining allowance L1 left, move the end mill 1 to grasp the current hole shape, and change the cutting setting in the radial direction from the current hole shape and the target target hole shape. Then, the current hole shape is grasped and the reworking is performed at least once until the target hole shape is obtained. [Selection diagram] Fig. 1

Description

  The present invention relates to a drilling method using an end mill that processes a hole having a target hole shape on a workpiece using an end mill.

  An end mill, which is a cutting tool, has a shape suitable for grooving so as to be used for processing of a side surface and a bottom surface. Therefore, since it is not suitable for drilling, drilling is usually performed using a drill.

  However, in recent years, the use of holes has been expanded, and required shapes such as a stop shape and a tapered shape have been diversified. In such a situation, hole machining using an end mill has been attracting attention as a convenient means for dealing with various hole shapes.

  As drilling using an end mill, machining that cuts from the top to the bottom like a drill and machining that creates a hole shape by circular interpolation of a predetermined dimension are generally used.

  For example, as in Patent Document 1, as a cutting tool for processing a work material, a ball end mill or a cutting tool in which a peripheral corner portion of a cutting edge provided at a tip forms a convex curve is used. A hole with an inner diameter larger than the tool diameter is obtained by rotating around the axis of the cutting tool while rotating around a circular orbit concentric with the center of the drilled hole. There is known a perforating method for forming the.

JP 2010-179379 A

  However, in the conventional method, since the side cutting edge of the end mill has machinability, the entire inner diameter is increased, and the influence of tool runout, chip clogging, tool collapse, and the like is shown in FIG. As shown in FIG. 8, the inner diameter is enlarged at the inlet portion, the inner diameter is enlarged only at the rear side as shown in FIG. 8, or the inner diameter is enlarged at both the inlet portion and the rear side portion as shown in FIG. It is difficult to finish the hole diameter accurately. When arc cutting is performed, due to insufficient rigidity of the end mill or the like, the back side is bent, so that the inner diameter of the back side is reduced, and a tapered hole cannot be formed.

  In addition, when the hole diameter is extremely small (for example, a wristwatch part), the gap gauge cannot be inserted, so that this shape cannot be confirmed during the cutting process. In such a case, the hole diameter is small and the tolerance is severe.

  This invention is made | formed in view of this point, The place made into the objective is to drill a hole precisely in the whole depth of a hole with an end mill.

  In order to achieve the above object, in the present invention, the end mill is brought into contact with the inner periphery of the hole to be processed and the hole is processed while grasping the inner diameter.

Specifically, in the first invention, in a drilling method using an end mill that processes a hole having a target hole shape on a workpiece using an end mill,
A preparation step of preparing the end mill having an outer diameter smaller than a target inner diameter of the target hole shape;
Applying a helical interpolation using the end mill, and a helical interpolation step of machining to a predetermined depth leaving a predetermined first diameter remaining margin;
A current hole shape grasping step of grasping the current hole shape by moving the end mill while leaving the first diameter remaining allowance;
A reworking step for reworking by changing the radial cutting setting from the current hole shape and the target hole shape;
The present invention includes a finishing process in which the current hole shape grasping process and the reworking process are performed at least once until a target hole shape is obtained.

  According to the above configuration, when machining a hole using helical interpolation, the machining is performed while leaving a large first diameter remaining allowance, so even if the end mill is bent during machining and the inner diameter is partially enlarged, there is a problem. There is no. And since the present hole shape after a helical interpolation process is grasped | ascertained with an end mill, and the amount of subsequent cuts is changed and it leaves and processes it, it can improve the fall of the processing precision by the inclination of an end mill, etc. At that time, since the end mill itself is detected by bringing it into contact with the inner surface of the hole, the current hole shape can be grasped without pulling the end mill out of the hole, which is efficient. Leave the allowance slightly larger in the helical interpolation process, grasp the current hole shape in the current hole grasping process, increase the depth of cut in the reworking process, and finally the current hole shape grasping process and reworking process in the finishing process Are performed at least once to finish to the target hole shape, so that the hole is accurately processed. Here, “end mill” means a tool portion for cutting a workpiece. In the finishing process, the current hole shape grasping process and the reworking process may be performed only once, or may be repeated several times.

In the second invention, in the first invention,
In the current hole shape grasping step, the end mill is brought into contact with the inner surface of the hole of the work at three positions so as to form a right triangle when viewed from the axial direction, and the current hole shape is grasped from the position coordinates of the three positions. To do.

  According to the above configuration, since the center position of the end mill can always be grasped by the machine tool, the current hole shape can be easily obtained from the trigonometric function by abutting at three places so as to draw a right triangle as viewed from the axial direction. Accurately grasp. The contact determination may be determined by, for example, an AE sensor, energization, power change, or the like.

In the third invention, in the first or second invention,
In the current hole shape grasping step, the current hole shape is grasped at a plurality of locations in the axial direction of the hole.

  According to the above configuration, for example, by measuring at three locations of shallow depth, middle and deep locations, it is possible to grasp the error from the target inner diameter of the current hole shape over the entire depth, and in the subsequent finishing process An appropriate depth of cut can be set according to the deformation.

In the fourth invention, in the third invention,
In the current hole shape grasping step, when it is determined that the inner diameter on the shallow depth side of the hole has increased, the second diameter remaining allowance smaller than the first diameter remaining allowance is left in the reworking step. After changing the depth of cut to machine the entire axial direction,
The process returns to the current hole shape grasping process again.

  According to the above configuration, the inner diameter on the shallow depth side of the hole that was drilled by helical interpolation with the first machining allowance increased, so the depth of cut is increased and especially the inner side is machined. . Thereafter, by repeating the current hole shape grasping step and the reworking step, the hole machining with a small change in the inner diameter in the axial direction is performed.

In the fifth invention, in the third invention,
In the current hole shape grasping step, when the inner diameter on the deeper side of the hole is enlarged, in the reworking step, a second diameter remaining allowance smaller than the first diameter remaining allowance is left. Change the depth of cut and machine the shallow side of the hole first, then machine the whole axial direction,
It is set as the structure which returns to the said present hole shape grasping process again.

  According to the above configuration, in the current hole shape grasping step, if the inner diameter on the deeper side of the hole is enlarged, the end mill does not contact the inner surface of the hole on the deeper side of the hole. In such a case, the cutting amount is increased so as to leave a second diameter remaining allowance smaller than the first diameter remaining allowance, and the shallow side of the hole is first processed. Thereafter, the entire axial direction is machined, and the current hole shape is grasped again, so that the hole machining is performed with high accuracy.

In a sixth invention, in any one of the first to fifth inventions,
The target hole shape is 0.07 mm or more and 1 mm or less.

  According to said structure, it is suitable for the process of a hole smaller than 1 mm in which a clearance gauge does not enter. On the other hand, holes with a diameter smaller than 0.07 mm are difficult to drill using an end mill.

  As described above, according to the present invention, with the first diameter remaining allowance remaining, the end mill is moved to grasp the current hole shape, the cutting amount is reset, and the machining is performed again. Thus, the end mill can accurately drill the hole in the entire depth.

It is a top view which shows a mode that a hole diameter is measured from three points of A, B, and C. FIG. It is the II-II sectional view taken on the line of FIG. 6 is a plan view illustrating a method for calculating the coordinates of a point A. FIG. It is a schematic sectional drawing which shows each process (a)-(e) which carries out a hole process with an end mill. It is the table | surface which showed the error of the hole diameter in a comparative example. It is the table | surface which showed the error of the hole diameter in an Example. It is sectional drawing which shows a mode that the internal diameter of the shallow depth side is expanding when drilling with an end mill. It is sectional drawing which shows a mode that the internal diameter of the deep side is expanding when drilling with an end mill. It is sectional drawing which shows a mode that the internal diameter of a shallow side and a deep side is expanding when drilling with an end mill.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 to 4 show a drilling method using an end mill 1 according to an embodiment of the present invention. Although not shown in detail, the end mill 1 is used for a known milling machine or the like, and in particular, one having a small tool outer diameter d such as a diameter of 0.05 mm is a main target. In the present embodiment, the target hole shape is, for example, a target inner diameter (target hole diameter) D0 of 0.07 mm to 1 mm.

  Next, a drilling method using the end mill 1 that processes a hole having a target hole shape in the workpiece 2 using the end mill 1 will be specifically described.

  First, in the preparation step, an end mill 1 having an outer diameter (for example, tool diameter d = 0.05 mm) smaller than a target inner diameter (for example, target inner diameter D0 = 0.16 mm) of the target hole shape is prepared first. The tool diameter d is accurately measured with a laser or a stereomicroscope.

  Next, in the helical interpolation step, helical interpolation is applied using the end mill 1, leaving a predetermined first diameter remaining allowance L1 (for example, L1 = 10 μm) as the inner diameter D1, and a predetermined depth (for example, H = 0.8 mm). ).

  Next, in the current hole shape grasping step, the end hole 1 is moved and the current hole shape is grasped while the first diameter remaining allowance L1 remains. Specifically, in the current hole shape grasping step, the end mill 1 is brought into contact with the inner surface of the hole of the work 2 at three positions so as to draw a right triangle ABC as viewed from the axial direction. That is, first, as shown in FIG. 4A, the end mill 1 is lowered to a predetermined shallow position. Then, at the upper position where the depth of the hole is shallow, as shown in FIG. 1, the center position of the end mill 1 first brought into contact with the inner surface of the hole is point A, and the point moves in parallel with point A and contacts the inner surface of the hole. Move to B, move further from point B in the vertical direction, and move to point C where it abuts. The center coordinates of the end mill 1 at these three points A, B, and C can be accurately grasped as the tool coordinates of the milling machine. For example, as shown in FIG. 3, the position of the point A can be grasped from the center position of the tool and the tool diameter d. In addition, what is necessary is just to grasp | ascertain the presence or absence of a contact by AE sensor, electricity supply, motive power change, etc., for example. As shown in FIG. 3, the X and Y coordinates of the point A are as follows: X = 1/2 (Dcosθ−dcosθ), where D is the inner diameter of the hole, d is the tool diameter, and θ is the angle relative to the center O. Y = 1/2 (Dsinθ−dsinθ). Similarly, the X and Y coordinates of the points B and C can be obtained. The tool diameter d has been checked in advance, and the inner diameter D1 of the current hole shape can be obtained by calculating backward from the position coordinates of the tool grasped by the milling machine.

  Next, as shown in FIG. 4B, the end mill 1 is inserted a little more, and the position coordinates of the three points A, B, and C are similarly grasped at the middle position.

  Further, as shown in FIG. 4 (c), the end mill 1 is inserted a little, and the position coordinates of the three points A, B, and C are similarly grasped at the lower position. Here, for example, when the hole shape has an inner diameter at the lower position larger than the inner diameter at the middle position as shown in FIG. 6 or FIG. 7, the end mill 1 does not contact at the lower position.

  In this way, in the current hole shape grasping process, it is possible to grasp the error from the target inner diameter of the current hole shape in the helical interpolation process by grasping the current hole shape in the upper, middle, and lower three locations in the axial direction of the hole. In addition, an appropriate cutting amount can be set in the subsequent finishing process.

  For example, the hole shape is simply divided into three patterns as shown in FIGS. There is a problem that the inner diameter of a part of the hole of the workpiece 2 in the depth direction increases due to the swing of the end mill 1, the end mill 1 falling, clogging of chips, and the like.

  As shown in FIG. 7, for example, in the current hole shape grasping process after processing with the first diameter remaining allowance L1 = 10 μm, it is determined that the inner diameter on the shallow depth side of the hole is larger than the original inner diameter D1. In the reworking step, the entire amount in the axial direction is processed from the middle to the bottom by changing the cutting amount so as to leave the second diameter remaining allowance L2 smaller than the first diameter remaining allowance L1. At this time, the second diameter remaining allowance L2 is set to a size that is aligned with the inner diameter on the shallower depth side, for example. Then, the process returns to the current hole shape grasping process again.

  Finally, in the finishing process, the current hole shape grasping process and the reworking process are performed at least once until the target hole shape is obtained. Further accuracy improvement can be achieved by gradually reducing the second diameter remaining allowance L2. Finally, the end mill 1 is finished by cutting, for example, about 5 μm to the bottom in the entire depth direction.

  In this way, first, the first diameter remaining allowance L1 is increased and drilling is performed by helical interpolation, and the drilling is performed by increasing the depth of cut, thereby performing drilling with a small change in the inner diameter in the axial direction. Can do. The finishing process may be performed only once. That is, after the reworking step, finishing may be performed by cutting about 5 μm at a stroke.

  As shown in FIG. 8, in the current hole shape grasping process, when it is determined that the inner diameter on the deeper side of the hole is expanding, as shown in FIG. Then, change the cutting setting in the radial direction from the target hole shape to be targeted and rework to the upper position and the middle position. Specifically, the second diameter remaining allowance L2 smaller than the first diameter remaining allowance L1 is first processed on the shallow side of the hole by changing the cutting amount so that the inner diameter becomes equal throughout the entire depth, Thereafter, the entire axial direction is machined, and the process returns to the current hole shape grasping process again to measure the inner diameter again. In this case, the second diameter remaining allowance L2 may be set larger than in the case of FIG. 7, and the processing may be repeated so as to gradually decrease the second diameter remaining allowance L2. Finally, the end mill 1 is finished by cutting, for example, about 5 μm to the bottom in the entire depth direction.

  As shown in FIG. 9, in the current hole shape grasping process, when it is determined that the inner diameters of the shallow and deep holes are increased, the tip of the end mill 1 is brought to the intermediate position in the depth direction to obtain the first diameter. The depth of cut is changed so that the second diameter remaining allowance L2 smaller than the remaining allowance L1 is left, and particularly the inner side is processed from the middle. Then, the process returns to the current hole shape grasping process again. Then, in the finishing process, the current hole shape grasping process and the reworking process are performed at least once until the target hole shape is obtained. For example, it is repeated a predetermined number of times, and finally the whole is cut from the upper position to the lower position by 0.5 μm.

  As described above, in the helical interpolation process, when machining a hole using helical interpolation, the machining is performed while leaving the predetermined first diameter remaining allowance L1, so even if the end mill 1 is bent during machining, there is a problem. There is no. In the current hole grasping step after the helical interpolation step, the current hole shape is grasped, and the cutting amount is set in the subsequent reworking step. Therefore, it is possible to improve the reduction in machining accuracy due to the inclination of the end mill 1 or the like. At this time, since the end mill 1 itself is brought into contact with the inner surface of the hole, the current hole shape can be grasped without pulling the end mill 1 out of the hole.

  Further, since the position of the end mill 1 can always be grasped by a machine tool, the current hole shape can be grasped easily and accurately by bringing it into contact at three places so as to draw a right triangle when viewed from the axial direction.

  This embodiment is suitable for processing a hole having a diameter smaller than 1 mm where a gap gauge does not enter such that the target hole shape is 0.07 mm or more and 1 mm or less. In addition, since it is very difficult to form the end mill 1 itself for a hole having a diameter smaller than 0.07 mm, it is difficult to perform hole machining using the end mill 1.

-Processing result-
Machining of Comparative Examples 1 to 8 in which a hole machining with a target inner diameter D0 = 0.16 mm and a depth H = 0.8 mm is machined by conventional helical interpolation machining, and Examples 1 to 8 in which machining is performed by the method of the above embodiment The error is shown in FIGS.

  In Comparative Examples 1-8, it turns out that especially the error of the upper position with a shallow depth is as large as 0.004-0.005 mm. On the other hand, in Examples 1 to 8, all errors except for Example 4 were within 0.001 mm, and it was found that drilling can be performed with very high accuracy.

  Therefore, according to the drilling method using the end mill 1 according to the present embodiment, the end mill 1 can be brought into contact with the inner surface of the hole and the end mill 1 can accurately perform the hole drilling in the entire depth of the hole.

(Other embodiments)
The present invention may be configured as follows with respect to the above embodiment.

  That is, in the above-described embodiment, the hole diameter is extremely small so that the inner diameter cannot be measured with a gap gauge, but the present invention is applicable even when the inner diameter can be measured with a gap gauge. It can be applied, and drilling with a small change in inner diameter can be performed in the whole axial direction.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or a use.

1 End mill
2 Work
L1 1st diameter remaining allowance
L2 Second diameter remaining allowance

Claims (6)

In a drilling method using an end mill that processes a hole with a target hole shape on a workpiece using an end mill,
A preparation step of preparing the end mill having an outer diameter smaller than a target inner diameter of the target hole shape;
Applying a helical interpolation using the end mill, and a helical interpolation step of machining to a predetermined depth leaving a predetermined first diameter remaining margin;
A current hole shape grasping step of grasping the current hole shape by moving the end mill while leaving the first diameter remaining allowance;
A reworking step for reworking by changing the radial incision setting from the current hole shape and the target hole shape to be targeted,
A drilling method using an end mill, comprising: a finishing step in which the current hole shape grasping step and the reworking step are performed at least once until the target hole shape is obtained. In the drilling method using the end mill according to claim 1,
In the current hole shape grasping step, the end mill is brought into contact with the inner surface of the hole of the work at three positions so as to form a right triangle when viewed from the axial direction, and the current hole shape is grasped from the position coordinates of the three positions. A drilling method using an end mill characterized by: In the drilling method using the end mill according to claim 1 or 2,
In the present hole shape grasping step, the present hole shape is grasped at a plurality of positions in the axial direction of the hole. In the drilling method using the end mill according to claim 3,
In the current hole shape grasping step, when it is determined that the inner diameter on the shallow depth side of the hole has increased, the second diameter remaining allowance smaller than the first diameter remaining allowance is left in the reworking step. After changing the depth of cut to machine the entire axial direction,
A drilling method using an end mill, wherein the process returns to the current hole shape grasping process again. In the drilling method using the end mill according to claim 3,
In the current hole shape grasping step, when the inner diameter on the deeper side of the hole is enlarged, in the reworking step, a second diameter remaining allowance smaller than the first diameter remaining allowance is left. Change the depth of cut and machine the shallow side of the hole first, then machine the whole axial direction,
A drilling method using an end mill, wherein the process returns to the current hole shape grasping process again. In the drilling method using the end mill according to any one of claims 1 to 5,
The said target hole shape is 0.07 mm or more and 1 mm or less, The drilling method using the end mill characterized by the above-mentioned.

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