JP2009045680A - Method for machining tilted fine hole - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for machining a fine hole tilted by a required angle on the workpiece made of relatively hard material, which method can form the fine hole having a furthermore large tilting angle and a furthermore large depth, and further can achieve the shape accuracy and the positional accuracy of a high level. <P>SOLUTION: In the method for machining a tilted fine hole, the fine hole is drilled such that the rotary axis of a drill is aligned with the expected drilling line X tilted with respect to the normal line for the surface of a workpiece 1, and the drill is fed with a required feed pitch. In this case, a guide hole 10a, which has nearly the same inside diameter as the diameter d of the drill, and suppresses the run-out of the rotary axis of the drill in the radial direction by holding the tip end portion of the drill, is provided by nearly cylindrically cutting the surface of the workpiece 1 using an end-mill 2 such that its central axis coincides with the expected drilling line X. Then the tip end portion of the drill 30a is inserted into the guide hole 10a, and the drilling process is started. Thus, the drilling position and the drilling direction are made so as to coincide with those of the expected drilling line X by guiding the drilling position and the drilling direction by means of the guide hole 10a in the approaching stage of the drilling work. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inclined fine hole machining method, and more particularly, to an inclined fine hole machining method for providing fine holes having a predetermined inclination in a workpiece made of a material having a relatively high hardness such as metal or ceramics.

  In recent years, a technique for providing fine holes (holes having a diameter of less than 0.3 mm) in a workpiece, which is a material to be processed, has become widespread, and is used for drilling semiconductor-based pores and medical device holes. Yes. For example, Japanese Patent Application Laid-Open No. 10-286708 discloses a method of providing a microhole with a diameter of about several tens of μm in a relatively short time by applying low-frequency vibration to the drill in a direction parallel to the cutting direction of the drill with respect to the workpiece. An apparatus is described.

  By using such a technique, it is possible to efficiently provide fine holes in the work with high accuracy. In addition, in order to provide a deeper and deeper hole using a thin and easy to break drill, every time the drill is fed a predetermined amount, the procedure of pulling it out from the workpiece is repeated to discharge chips (cutting chips) to the outside. The cutting ability is maintained while avoiding an increase in resistance due to blade clogging and the occurrence of cutting defects.

  However, in order to implement such a technique, a dedicated drilling device in which vibration generating means for applying low-frequency vibration parallel to the feed direction is provided on the feed means for moving the machining head up and down is required. As a result, since a general apparatus cannot be used as it is, a new capital investment is required, resulting in an increase in cost.

  This processing method basically assumes the case where fine holes are provided perpendicular to the workpiece surface, and fine holes inclined at a predetermined angle or more with respect to the vertical line of the processed surface are provided in a relatively hard workpiece. In this case, a weak drill is bent in the centrifugal direction at the initial stage of cutting when the tip of the drill comes into contact with the workpiece surface in an inclined manner, and the tip is displaced or broken. For this reason, the work efficiency is remarkably lowered, and the shape accuracy and position accuracy of the fine holes obtained are extremely lowered, and the expected work result cannot be obtained in many cases.

  In response to this problem, Japanese Patent Application Laid-Open No. 2003-260611 discloses that by using a drill whose tip is hemispherical or whose apex angle is twice the tilt angle with respect to the machining surface, a preliminary machining hole is provided in the workpiece. An inclined hole machining method has been proposed that enables an inclined hole to be provided with high positioning accuracy during drill cutting.

  However, the pre-processed hole by this processing method does not hold the tip of the drill so that the drill rotation axis does not move in the centrifugal direction from the planned cutting line, but merely forms a vertical surface on the workpiece surface with respect to the drill rotation axis. belongs to. Therefore, when an inclined micro hole is provided in a hard workpiece using a micro drill for a micro hole that bends and breaks with a slight force, trouble of drill breakage occurs frequently even with a slight error. Further, in this case, a slight misalignment of the tip of the drill leads to a significant decrease in machining accuracy, and is insufficient as a means for providing a precise inclined fine hole.

  Furthermore, in common with the technique of providing the inclined fine holes using the existing processing method, as shown in the enlarged vertical sectional partial view of FIG. When a part of the tip end side of the drill 30 is exposed on the back surface, the receiving surface 100 is formed at the tip end of the drill 30 on the opposite side of the exposed position, so that the tip end portion of the drill 30 moves on the receiving surface 100 toward the side with less resistance. As a result, the drill 30 itself is curved and a deviation from the planned cutting line X occurs.

Therefore, as shown in FIG. 9 (B), the trouble that the tip of the drill 30 breaks in the middle of the penetrating operation while shaking in the direction of the arrow frequently occurs. In addition, when the tip of the drill 30 penetrates to the back surface, turning edge 101 and cracks are formed at the edge of the opening, and the fine hole 10 itself is also curved at the exit portion, so that the finished shape accuracy is extremely deteriorated. Become.
JP-A-10-286708 JP 2003-260611 A

  The present invention is intended to solve the above-described problems, and an inclined fine hole processing method for providing fine holes inclined at a predetermined angle in a workpiece made of a relatively hard material has a larger fine hole. It is an object of the present invention to make it possible to achieve a high level of shape accuracy and position accuracy while enabling deeper drilling at an inclination angle.

  In view of this, the present invention provides an inclined microhole machining in which microholes are drilled while feeding at a predetermined feed pitch so that the rotation axis of the drill coincides with a planned cutting line inclined at a predetermined angle with respect to a vertical line to the workpiece surface. In this method, a guide hole that has an inner diameter that is approximately the same size as the diameter of the drill and that holds the tip of the drill and restricts the movement of the rotation axis in the centrifugal direction is used to make the central axis the planned cutting line using an end mill. The drill is cut by the guide hole in the approach process of drilling as the drill cutting process is started by inserting the tip of the drill into the guide hole and then starting the drill cutting process. The position and cutting direction are guided to match the planned cutting line.

  That is, when providing a pre-machined hole with a center drill when providing an inclined fine hole with a fine drill for a relatively hard work, if the inclination angle is large, the tip of the drill bites into the inclined surface of the work It is difficult to make a pre-processed hole accurately by sliding, curving or shifting, and the rotation axis is correct because the tip is not held even if the drill abuts the bottom surface of the pre-processed hole. Whereas it is difficult to guide in the position and direction, when the guide hole is provided in the end mill as described above, the cutting surface is perpendicular to the rotation axis of the end mill.・ Because it is possible to drill in a cylindrical shape at an angle and depth, the inserted drill tip is regulated in the guide hole and guided in the correct position and direction, so errors and troubles In prone drilling operation early stage, so enabling highly accurate cutting.

  In addition, in this machining method, when providing a fine hole penetrating to the back side of the workpiece, the range from the point immediately before the tip end side of the drill is exposed to the back side of the drill to the point where the tip of the drill penetrates completely is fed. If it is characterized by carrying out profile processing that repeats the operation of rotating a predetermined distance and rotating it a predetermined distance several times without operation, drill breakage or opening when the drill penetrates the back of the workpiece The deformation of the part can be effectively avoided. In this case, according to the profile processing, if the rotation without feeding operation is 1 to 2 rotations and the feeding distance while rotating is 0.5 μm to 1.5 μm, respectively, it corresponds to the inclination level of the micropores. Therefore, it is easy to ensure the shape accuracy of the back side opening.

  Further, in the above-described inclined fine hole drilling method, at the time of the drill cutting process, every time the drill is fed into the workpiece for a predetermined distance, the drill is pulled out and replaced with a new one, and then the operation is continued. If this is the case, the reduction in cutting ability due to clogging of the cutting blade into the drill blade will be maintained by cutting the cutting powder when the drill is pulled out and replacing it with a new drill according to the wear of the blade. And deeper cutting can be performed.

  Furthermore, in the above-described inclined fine hole machining method, the drill rotation speed in the drill cutting process is 7500 rpm to 12500 rpm, and the feed pitch is in the range of 1.0 μm to 6.0 μm depending on the material hardness of the workpiece and the drill diameter. If it is selected, it is easy to avoid a drill breakage trouble while ensuring a predetermined work efficiency.

  According to the present invention, the end hole is provided with a guide hole for holding the drill tip and guiding the cutting position and direction in the previous stage of the drill cutting process. According to the present invention, the fine hole is formed deeper with a larger inclination angle. While being possible, the shape accuracy and position accuracy can be achieved at a high level.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 to FIG. 4 are longitudinal sectional views for explaining the procedure of the inclined fine hole machining method according to the embodiment of the present invention. Referring to FIG. 1, the inclined fine hole machining method of the present embodiment is provided with a fine hole having a diameter of less than 0.3 mm, particularly 0.1 mm or less, on a work 1 made of a relatively hard material such as stainless steel or ceramics. Along the planned cutting line X at a depth of a hole length g of diameter d × 5 or more at an inclination angle θ in the range of 0 ° to 45 °, particularly 40 ° to 45 ° with respect to the vertical line to the surface of the workpiece 1 In this case, the accuracy of the shape of the fine hole 10 to be obtained is within the tolerance range of the planned hole diameter ± 5%.

  The feature of the process is substantially the same as the diameter d for regulating the drill rotation axis so as not to move in the centrifugal direction and guiding the cutting position and direction in the initial introduction stage (approach process) of the drilling process by the drill 30a. The size of the guide hole 10a is formed in a substantially cylindrical shape by using the end mill 2 and then drill cutting is performed. In this case, if the guide hole 10a is larger in diameter than the diameter d, the drill 30a is loosely moved inside, and an error is likely to occur in the cutting position / cutting direction of the drill 30a, and the opening of the micro hole is enlarged from the beginning. When the diameter is smaller than the diameter d, the precision of the drill is reduced, and when the inclination angle is large, the drill tip becomes slippery and is not easily held in the correct position.

  In addition to this feature, the drill 30c is replaced with a new one for each feed amount c in the drill cutting process. A characteristic feature is that so-called profile processing is performed in a range from immediately before a portion of the tip side is exposed to the back surface until the tip portion completely penetrates.

  In each of the following processes, the use of an appropriate cutting oil (machine oil) at the time of cutting, and the finishing process such as deburring and polishing of both openings of the fine holes are almost the same as the prior art. Therefore, detailed description is omitted. Further, since the general apparatus can be used as it is for the configuration and function of the drilling apparatus having the workpiece fixing means, the motor, the machining head, the feeding means, etc., detailed description thereof will be omitted.

  First, the approach process will be described with reference to FIGS. The workpiece 1 is supported and fixed by the workpiece fixing means at a relatively large inclination angle θ of, for example, 40 ° to 45 ° with respect to the horizontal plane, and the fine holes 10 are formed along the planned cutting line X having the inclination angle θ with respect to the vertical line. In the processing method to be provided, the approach step is performed at an initial stage in the cutting operation. In this case, a substantially cylindrical guide hole 10a is drilled at a predetermined depth b along the planned cutting line X using an end mill 2 having a diameter basically the same as the diameter d of the drill used for drilling. It is preferable to install. That is, it is possible to enlarge the hole diameter to the size of the guide hole by using an end mill having a diameter smaller than the drill diameter d (= the diameter of the guide hole), but it requires extra labor and time.

  In the drilling of the guide hole 10a by the end mill 2, the rotation speed and the feed pitch are appropriately set according to the diameter, the hardness of the workpiece 1 and the inclination angle θ. For example, the feed pitch may damage the end mill 2. From the viewpoint of ensuring a predetermined work efficiency while avoiding, when the workpiece 1 is stainless steel and the inclination angle is 40 ° to 45 °, about 1.0 μm is usually appropriate.

  Referring to the enlarged partial views of FIGS. 3A and 3B, the depth b of the guide hole 10a drilled by the end mill 2 is the vicinity of the lower end line 310 of the outer peripheral surface when the tip of the drill 30a is inserted. The length of the portion (arc) in contact with the inner peripheral surface of the guide hole 10a exceeds 50% of the outer periphery of the drill 30a as shown in the plan view of FIG. The range Y is set to a depth at which a substantially cylindrical hole that can be held by the inner peripheral surface is formed.

  Thereby, when the drill 30a is driven, the rotation axis is regulated and fixed so as not to float in the centrifugal direction. That is, in the conventional example, when a pre-processed hole is provided with a center drill to make an inclined fine hole, if the workpiece has a high material hardness or a large inclination angle, the drill slides on the inclined surface and bends or breaks. For this reason, it was unavoidable that the drill had to be provided perpendicular to the workpiece surface, and because it was a shallow hole, it was difficult to guide the drill to the correct cutting position and direction in subsequent cutting. In the form, the cylindrical guide hole 10a is provided at the depth b, so that the cutting position and direction of the drill are correctly guided in the initial stage of the drilling process by the drill 30a, so that a highly accurate cutting operation can be performed. It is what.

  Next, the cutting process using the drills 30a, 30b, and 30c will be described in more detail with reference to FIG. 1 again. In this cutting process, the drill rotation speed ranges from 7500 rpm to 12500 rpm depending on the drill diameter and the material hardness of the workpiece 1. The feed operation is repeated while setting the feed pitch in the range of 1.0 μm to 6.0 μm. Thereby, breakage of the drill can be avoided while ensuring a predetermined level of work efficiency, and fine holes can be drilled with high accuracy. In addition to this, there is a procedure for removing the drill and replacing it with a new one for each predetermined feed amount c set according to the clogging of the cutting chips and the wear state of the cutting edge.

  That is, when the first drill 30a is cut by feeding the feed amount c, it is removed and replaced with a new drill 30b. The drill 30b further feeds the feed amount c and cuts it. Similarly, the drill 30b is replaced with a new drill 30c, and the feed hole c is further fed and cut to penetrate the fine hole 10. By adopting such a procedure, every time the drill is pulled out, chips clogged between the blades are discharged to the outside, and it becomes possible to increase the working efficiency by reducing the cutting resistance. In addition, by replacing with a new drill, the state in which the blade is worn and heated to reduce the cutting function can be eliminated at the same time, and a deeper fine hole can be efficiently provided with a thinner drill.

  The profile process, which is the final stage of the drilling process, will be described with reference to FIG. In the conventional inclined fine hole processing method, when the inclined fine hole is provided penetrating to the back surface of the work 1, as shown in FIG. Troubles in which the inclined surface (cutting surface) of the tip slides on the top and the tip of the drill 30 bends to the side with less resistance and breaks easily, and the shape of the hole is extremely lowered due to deformation and breakage of the opening. Was produced.

  Therefore, in the present embodiment, as shown in FIG. 4, the range of the width f from immediately before the drill 30c tip side portion (corner portion) is exposed to the back surface of the work 1 until the drill 30c tip portion completely penetrates, After a predetermined number of rotations without the feed operation of the drill 30c, a so-called profile machining step is repeated in which the feed operation is repeated a plurality of times while rotating a predetermined distance.

  For example, when the workpiece 1 is a material having a relatively high hardness such as stainless steel and the inclination angle θ of the fine hole is relatively large as 40 ° or more, the workpiece 1 is rotated at a rotational speed of about 10000 rpm with a drill 30c having a diameter of 0.10 mm or less. When penetrating to the back surface, the width f by profile processing is about 1.0 to 1.5 times the drill diameter d.

  The rotation without feeding operation in this profile processing is usually 1 to 2 rotations, and the feeding pitch while rotating is usually about 1.0 μm. This is because if the rotation without feeding operation exceeds two times, the cutting of the blade tends to be worse, and if the feeding pitch exceeds this, the drill 30c is likely to be bent and broken.

  The above-described steps can be carried out using a general drilling device as it is, so that it is not necessary to newly introduce a dedicated device. Moreover, since excessive labor and time are not required in the process, the process can be carried out without excessively increasing the cost. And by carrying out the inclined microhole machining method of the present embodiment, it is possible to provide deeper finer holes with a larger inclination angle deeper for a relatively hard work without requiring special skill, It is possible to achieve the hole shape accuracy and position accuracy at a high level.

  Hereinafter, the present invention will be described in more detail with reference to examples. FIG. 5 is a longitudinal sectional view for explaining the procedure of the inclined fine hole processing method in the present embodiment. As can be seen from the figure, this example specifically implements the contents of the above-described embodiment, and the configuration of the work procedure is the same. Then, the accuracy of the holes thus obtained was examined by confirming the arrangement state of the micropores from the appearance photograph and measuring each hole diameter from the micrograph of the micropore opening.

(Implementation content)
Work material (work 1) Material: SUS SK5, Hardness: HRA50 or more, Thickness: 0.4mm b. Work target (micro hole 10) Hole shape: Diameter (d) 0.100mm x Hole length (g) 0.566mm x 8 pieces (circular arrangement), inclination angle: 45 °, accuracy: within 5% tolerance to the planned hole diameter c. Drill (30a, 30b, 30c) Diameter: 0.10mm, Blade length: 0.8mm, Product Name: Micro Drill NSMD, manufactured by Nisshin Tool Co., Ltd., sold by FA System d. End Mill (2) Diameter: 0.10 mm, Blade Length: 0.5 mm, Product Name: NSME 230, manufactured by Nisshin Tool Co., Ltd., sold by FA System e Approach process (end mill cutting part) Rotational speed: 10000 rpm, feed pitch: 1.0 μm, depth (b): 0.025 mm, tilt angle: 45 °, equipment used: MAKINO V22 f. Cutting process Rotational speed: 10000 rpm, feed pitch: 1.0 μm, feed amount c: 0.200 mm (c × 3 = 0.600 mm), tilt angle: 45 °, profile processing: (2 rotations + feed width 1.0 μm) × 120 Times (width f, 0.120 mm), cutting oil: non-volatile oil, product name: Yusilon cut Arbus BM405, equipment used: MAKINO V22

(result)
Penetration was confirmed in all the fine holes (eight), and as shown in the microphotograph of the micropore front side opening in FIG. 6 and the microphotograph of the microhole back side opening in FIG. The shape accuracy of was obtained. Further, as shown in the graph of FIG. 8, the accuracy of the holes was achieved within a tolerance of ± 0.005 mm (5%) from the actually measured hole diameter.

  In the above-described embodiment, the inclination angle of the fine hole was 45 °, but the present invention is not limited to this range, and according to conditions such as the drill diameter and the hardness of the workpiece, the hole length, etc. Naturally, when the inclination angle is smaller than this, it may be possible to implement even in a situation where the inclination angle is large, and the above-described effects can be expected.

  As described above, with respect to the inclined microhole processing method for providing the microholes with a predetermined inclination angle in the relatively hard work, according to the present invention, the microholes can be drilled deeper with a larger inclination, The hole shape accuracy and position accuracy could be achieved at a high level.

The longitudinal cross-sectional view for demonstrating the procedure of the inclination fine hole processing method of embodiment in this invention. The longitudinal cross-sectional view for demonstrating the approach process in the procedure of FIG. (A) And (B) is the expanded longitudinal cross-sectional view for demonstrating the detail of the approach process of FIG. 2, (C) is a top view of the guide hole of (A). The expanded longitudinal cross-sectional view for demonstrating the profile process in the procedure of FIG. FIG. 3 is a longitudinal sectional view for explaining the procedure according to the first embodiment. FIG. 3 is a front micrograph of micropores obtained in Example 1. FIG. 2 is a backside micrograph of micropores obtained in Example 1. FIG. The graph which shows the hole diameter measurement result of the front side opening part and back side opening part of the micropore obtained by Example 1. FIG. (A) And (B) is a longitudinal cross-sectional view for demonstrating a prior art example.

Explanation of symbols

  1 Workpiece, 2 End mill, 10 Fine hole, 10a Guide hole, 30a, 30b, 30c Drill

Claims (5)

In the inclined microhole machining method of drilling microholes in the workpiece while feeding at a predetermined feed pitch so that the rotation axis of the drill coincides with a planned cutting line inclined at a predetermined angle with respect to a vertical line to the workpiece surface,
A guide hole that has an inner diameter substantially the same as the diameter of the drill and holds the tip of the drill and restricts the free movement of the rotation axis in the centrifugal direction, and the center axis is set to the planned cutting line using an end mill. It is provided by cutting into a substantially cylindrical shape from the workpiece surface so as to match, and then inserting the tip of the drill into the guide hole to start the drill cutting process. An inclined fine hole machining method characterized by guiding a cutting position and a cutting direction of the drill so as to coincide with the planned cutting line.   When the fine hole is provided penetrating to the back surface of the work, a feed operation of the drill is performed in a range from immediately before a part of the tip side of the drill is exposed to the work back surface until the tip of the drill completely penetrates. 2. The inclined micro-hole machining method according to claim 1, wherein the profile machining is performed by repeating a plurality of rotations after a predetermined number of rotations without rotating and a predetermined distance.   3. The inclination according to claim 2, wherein in the profile processing, the rotation without the feeding operation is 1 to 2 rotations, and the feeding distance while rotating is 0.5 μm to 1.5 μm, respectively. Micro hole processing method.   The work is continued after the drill is pulled out and replaced with a new one every time the drill is fed into the workpiece by a predetermined distance during the drill cutting process. 4. The method for machining inclined micropores described in 1.   The drill rotation speed in the drill cutting step is 7500 rpm to 12500 rpm, and the feed pitch is selected in the range of 1.0 μm to 6.0 μm according to the material hardness of the workpiece and the diameter of the drill. 5. The method for processing inclined fine holes according to claim 1, 2, 3, or 4.