JP2014054678A - Finishing processing tool for prepared hole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cutting tool that enables a prepared hole with a concavo-convex part on an inner peripheral surface thereof to be processed by cutting into a high-accuracy finished hole in a short time and has a long service life.SOLUTION: A finishing processing tool for a prepared hole comprises: a tool main body 34 whose outer periphery has at least three cutting blades; and at least three guide pads 32 provided at equal angles and intervals respectively as much as possible. Each guide pad 32, which is in a posture of axially extending and in a position nearer a base end of the tool main body 34 than each of the cutting blades, is slidably connected to an inner peripheral surface of a finished hole formed by cutting processing using the cutting blade to guide the tool main body 34. In each of the guide pads 32 is formed a coolant outlet 96, which extends along a lateral side 84 facing forward in a rotation direction, from which coolant is blown out toward the inner peripheral surface of the finished hole so as to preferably prevent a chip 100 from being engaged between a slidably connected surface 106 of the guide pad and the inner peripheral surface of the finished hole, therefore increasing the service life of the slidable connected surface 106.

Description

  The present invention relates to a tool that finishes an inner peripheral surface of a pilot hole by cutting, and in particular, drilling with a large variation in cutting resistance with respect to a cutting tool such as a cast hole of an aluminum or cast iron casting. In addition, the present invention relates to a cutting tool capable of performing hole drilling that is intermittently cut with high accuracy and efficiency because recesses such as lubrication grooves and key grooves are formed on the inner peripheral surface of the prepared hole.

  Conventionally, in order to make a pilot hole with low dimensional accuracy a cutting hole that can satisfy the required accuracy (hereinafter referred to as a finishing hole) with a cutting tool held in a cantilevered state by a tool holding device, rough cutting is conventionally performed. In addition, it requires two steps of finish cutting and inevitably increases the time required for processing. In addition, in some cases, both roughing equipment and finishing equipment are required, which may increase equipment costs.

  As one of measures for coping with this problem, for example, three or more cutting edges are provided at equiangular intervals on the outer periphery of the tool body, and guide pads are provided between the cutting blades adjacent to each other. Cutting tools are being used. The cutting tool described in the following Patent Document 1 is an example, and if this type of cutting tool is used, the radial component of the cutting resistance is well balanced as the whole cutting tool and is formed by cutting with a cutting edge. Since the guide pad slides on the inner peripheral surface of the finishing hole to guide the cutting tool, a highly accurate finishing hole can be obtained.

JP 2006-150535 A

However, as a result of experiments by the inventors, chips generated by cutting are bitten between the sliding contact surface of the guide pad and the inner peripheral surface of the finish hole, and scratches are generated on the inner peripheral surface of the finish hole. It has been found that there may be inconveniences such as reducing the life of the guide pad.
Therefore, as shown in FIG. 11, a large number of coolant injection holes 162 arranged along the guide pad 160 are formed at a position forward in the direction of relative rotation with respect to the finishing hole of the guide hole finishing tool of the guide pad 160, or FIG. 12, a longitudinal coolant jet 168 extending in parallel to the longitudinal direction of the guide pad 164 is formed at the center of the sliding contact surface 166 of the guide pad 164, and the coolant is discharged from the coolant jet holes 162 and the coolant jet 168. Tried to erupt. As a result, it was confirmed that the chip could be prevented to some extent between the sliding surface of the guide pad and the inner peripheral surface of the finishing hole, but at the same time, it was found that it was still not sufficient. .
In the present invention, against the background described above, the radial component of the cutting resistance is well balanced as a whole, and the cutting pad is slidably contacted with the inner peripheral surface of the finished hole formed by cutting with the cutting blade. In a cutting tool that can obtain a highly accurate finished hole by guiding, it is possible to further prevent chips from being caught between the sliding contact surface of the guide pad and the inner peripheral surface of the finished hole. It was made as an issue.

This problem is a cutting tool that is held in a cantilevered manner by a tool holding device in a held portion, and that cuts the inner peripheral surface of a prepared object's prepared hole in the cutting portion, where the cutting portion is (a ) Three or more cutting blades provided at an equiangular interval as possible on the outer periphery of the tool body, and (b) an attitude extending in the axial direction at an equiangular interval as much as possible on the outer periphery of the tool body, In addition, each of the cutting blades is positioned closer to the holding portion with respect to the axial direction, and is in sliding contact with the inner peripheral surface of the finished hole formed by cutting with the cutting blade, and is cut into the finished hole. A pilot hole finishing tool including three or more guide pads for guiding a portion; and (c) each of the three or more guide pads in a rotational direction relative to the finish hole of the pilot hole finishing tool. Along the front, which is the front-facing surface, and each guide Respectively provided in a state extending continuously over substantially the entire length of the head, it is solved by shall include coolant spout for ejecting toward the inner circumferential surface of the hole finishing coolant.
The cutting blade and the guide pad need to be three or more in order to perform their functions satisfactorily. If the diameter of the pilot hole to be machined is relatively small, the diameter of the machining tool is also limited to a small size. Therefore, it is difficult to increase the diameter to more than three because of the structure, but as the diameter of the pilot hole increases, the diameter is increased to more than three. And it is often desirable to do so. And when there are three each of the cutting blade and the guide pad, it is inevitable that one guide pad is provided between the adjacent ones of the cutting blades in the circumferential direction of the tool body. When more cutting blades and guide pads are provided, the number of either one can be larger than the other.

  In principle, it is desirable to provide the cutting blades at equiangular intervals in order to balance the radial component of the cutting force as a whole tool, and to ensure that the guide pad performs the guide function satisfactorily. For example, when machining a pilot hole with two lubrication grooves separated in the diametrical direction by a machining tool having four guide pads provided at equiangular intervals, a pair of guide pads are used for lubrication. In a state of facing the groove, the other pair of guide pads are in sliding contact with two substantially parallel positions separated from each other in the diameter direction of the finishing hole, and the guide pad guiding function is substantially lost. Time may occur. Also, with regard to the cutting blade, at the time when the plurality of cutting blades cut the inner peripheral surface of the pilot hole, the plurality of cutting blades positioned on the opposite side of the plurality of cutting blades are just opposite to the recesses on the inner peripheral surface. As described above, there may be a period when a significant imbalance of the radial component of the cutting force occurs. For the purpose of avoiding the occurrence of such a situation, it may be desirable to intentionally change the arrangement interval of the guide pad and the cutting blade from an equal angle to an unequal angle. “In angular spacing” means that in such a case, the amount of deviation from the principle of equiangular spacing is as small as possible, but not even unequal angular spacing is excluded.

In the processing tool according to the present invention, the radial component of the cutting resistance is well balanced as the entire processing tool, and the guide pad slides on the inner peripheral surface of the finished hole formed by cutting the cutting edge. In order to guide, it is possible to enjoy the advantages of conventional machining tools that can obtain a finished hole with high accuracy, and scratches are generated on the inner peripheral surface of the finished hole, and the life of the guide pad is reduced. The occurrence of inconvenience can be satisfactorily prevented.
The coolant spout is formed so as to extend continuously along the front surface of each guide pad over substantially the entire length of the guide pad, so that the coolant sprays along the front surface of the guide pad toward the inner peripheral surface of the finish hole. However, since the sliding surface of the guide pad is in sliding contact with the inner peripheral surface of the finish hole, the gap between the guide pad and the inner peripheral surface is negligibly small, and the coolant is inevitably in the guide pad. It must flow in the direction away from the front. That is, as the pilot hole finishing tool and the pilot hole rotate relative to each other, the guide pad advances relative to the inner peripheral surface, but the coolant moves to the inner peripheral surface at a speed higher than the advance speed of the guide pad. In contrast, as shown in FIG. 12, it is easy to increase the amount of coolant injection as compared to the case where the coolant outlet 168 is formed on the sliding contact surface 166 of the guide pad 164. Therefore, the chips formed by the cutting blades in front of each guide pad are strongly washed away to prevent the chips from being caught in the gap between the sliding surface of the guide pad and the inner peripheral surface of the finishing hole. As a result, scratches caused by the biting of chips on the inner peripheral surface of the finished hole and a decrease in the life of the guide pad can be satisfactorily prevented.
In order to obtain this effect, it is desirable that the coolant jet port is formed so as to extend over the entire length of the guide pad. For example, as in the embodiment described later, the guide pad protrudes from the tip surface of the tool body. If it is not possible to form the entire length because it is provided or the like, the ejection port may be shorter than the guide pad. Even in such a case, not all of the coolant ejected from the ejection port flows in a direction perpendicular to the front surface of the guide pad, and part of the coolant flows in a direction having a longitudinal component of the guide pad. Chip biting is prevented. Therefore, the coolant jet outlet may be formed with a length of 80% or more of the total length of the guide pad, and is preferably 90% or more. The term “almost over the entire length” means this.

FIG. 1 is a front view of a pilot hole finishing tool (hereinafter abbreviated as a cutting tool) according to an embodiment of the present invention (however, in order to avoid complications, only cutting blades and guide pads separated from each other in the diametrical direction are illustrated. The illustration of the cutting blade and the guide pad in the middle of them is omitted). It is a front view which expands and shows the 1st step processed part and 2nd step processed part in FIG. It is A arrow directional view in FIG. 2 of the 1st step processed part of the said cutting tool. It is BB sectional drawing in FIG. 2 of the 2nd step processed part of the said cutting tool. It is C arrow line view in FIG. 2 of the said cutting tool. It is DD sectional drawing in FIG. 5 of the said cutting tool. (a), (b) It is a figure for demonstrating the function of the chip removal in the guide pad vicinity of the said cutting tool. It is a figure which shows the to-be-processed hole processed with the said cutting tool, (a) is a side view, (b) is EE sectional drawing in (a), (c) is the F section enlarged view in (b). is there. (a), (b), (c) It is explanatory drawing for demonstrating the working accuracy improvement principle by the special usage method of the said cutting tool. It is a figure which shows the movement image of the guide pad adjacent to the cutting blade in the special usage method of the said cutting tool. It is a front view which shows an example of the chip | tip prevention | intrusion prevention measure to the sliding contact surface of the guide pad which the inventor tried in the process of this invention completion. It is a diagram showing another example of the prevention of chips and penetration into the sliding contact surface of the guide pad that the present inventors tried in the process of completion of the present invention, (a) is a front view, (b) is (a) (B) is a cross-sectional view taken along line HH in (b).

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In addition, the present invention can be implemented in a mode in which various modifications are made based on the knowledge of those skilled in the art, in addition to the following embodiments.
In the present embodiment, the stepped pilot hole 2 shown by a two-dot chain line in FIG. 8 formed in an aluminum casting is finished with a single cutting tool and finished into a stepped finished hole 4 shown by a solid line. is there. A chamfer 8 is formed in advance in the stepped pilot hole 2. In this embodiment, the inner peripheral surface of the small diameter portion 10 and the large diameter portion 12 is finished, the shoulder surface 14 of the stepped portion and the Nusumi 16 Cutting with the chamfer 17 of the opening end of the large diameter portion 12 is performed. Further, the inner peripheral surface of the small-diameter portion 10 and the inner peripheral surface and shoulder surface 14 of the large-diameter portion 12 are formed with recesses 18 and 19 to be lubrication grooves at two locations separated in the diameter direction. Cutting is intermittent at these points.

  FIG. 1 shows an entire cutting tool 20 according to the present embodiment. The cutting tool 20 includes a taper shank 22 as a base end portion held by a tool holding device (not shown), and cuts on the free end side. A processing part is provided. The cutting portion includes a first step processing portion 24 that processes the small diameter portion 10 of the stepped pilot hole 2 and a second step processing portion 26 that processes the large diameter portion 12. Although the casting which is a workpiece may be rotated, in this embodiment, the cutting tool 20 shall be rotated.

  As is apparent from FIG. 3, the first stage machining unit 24 includes three cutting blades 30 and three guide pads 32. The three cutting blades 30 are arranged on the outer periphery of the tool body 34 at an angular interval of 120 °, and one guide pad 32 is provided at a central position between two adjacent ones of the three cutting blades 30. After all, the guide pads 32 are also arranged at an angular interval of 120 °. The cutting blade 30 cuts the inner peripheral surface of the small diameter portion 10, and the guide pad 32 slides on the inner peripheral surface of the small diameter portion 10 finished by the cutting blade 30 to guide the cutting tool 20. Is.

  As apparent from FIGS. 2 and 3, each cutting blade 30 is formed by a cutting tip 38 that is detachably attached to the cartridge 36, and the cartridge 36 is attached to a mounting seat of the tool body 34 by a fastening screw 40. 42, a spacer 44 is interposed between the cartridge 36 and the mounting seat 42, and an adjustment piece 50 is provided between the guide groove 48 formed in the mounting seat 42 and the spacer 44. Intervened. The surfaces of the bottoms of the guide groove 48 and the adjustment piece 50 that are in contact with each other are inclined with respect to the central axis of the tool body 34, and an adjustment screw 52 is interposed between the adjustment piece 50 and the tool body 34. It has been. The pitches of the two screw portions screwed into the adjustment piece 50 of the adjustment screw 52 and the tool main body 34 are different from each other (may be left and right reverse screws), and the adjustment piece 52 is rotated by rotating the adjustment screw 52. The position of 50 in the guide groove 48 is changed, and the position of the cutting blade 30 in the radial direction (the radial direction of the cutting tool 20; hereinafter the same) is adjusted. Further, the position of the cutting blade 30 in the axial direction (the axial direction of the cutting tool 20; hereinafter the same) is screwed into the cartridge 36 and the head is brought into contact with the receiving surface of the tool body 34. Adjustment is made by changing the axial position of the cartridge 36 by rotating the screw 54.

In addition, since the edge on the free end side of the cutting blade 30 is positioned slightly on the free end side with respect to the free end side end surface of the guide pad 32 in the axial direction, the cutting tool 20 is provided with a stepped pilot hole. 2 (this direction is taken as the forward direction), the guide pad 32 always comes into sliding contact with the inner peripheral surface of the hole cut by the cutting blade 30, and when the cutting tool 20 is retracted, the cutting blade 30. Touches the inner peripheral surface of the portion that is out of the guide pad 32, but does not perform substantial cutting. The change in the axial position of the cartridge 36 by the rotation operation of the adjusting screw 54 can be used for adjusting the axial position of the cutting blade 30 with respect to the guide pad 32.
In addition, the radial position of the cutting edge 30 can be adjusted by exchanging the spacer 44 with a different thickness or grinding the spacer 44.

  On the other hand, as shown in FIGS. 2 and 3, the guide pad 32 is attached to the mounting seat 62 by a tightening screw 60, but an adjustment wedge 64 is interposed between the mounting seat 62 and the guide pad 32. The adjustment wedge 64 is moved along the mounting seat 62 so that the radial position of the guide pad 32 can be adjusted. As shown in enlarged views in FIGS. 5 and 6, the tool body 34 is formed with a female screw hole 66 inclined with respect to the axial direction, and an adjustment screw 68 is screwed into the female screw hole 66. Although the female screw hole 66 is partially cut away as shown in FIG. 5, the female screw hole 66 and the adjustment screw 68 are screwed together at a portion exceeding a half circumference. On the other hand, the adjustment wedge 64 is formed with a notch 70 that engages with each part of both end faces of the adjustment screw 68. As the adjustment screw 68 is advanced and retracted in the female screw hole 66 by a rotation operation, the adjustment wedge 64 is moved. Is moved forward and backward along the mounting seat 62, whereby the guide pad 32 is moved in the radial direction by translation and the radial position is adjusted. For this purpose, a long hole 72 is formed in the middle portion of the adjustment wedge 64 in the longitudinal direction so that the movement of the adjustment wedge 64 is not hindered by the fastening screw 60.

  The mounting seat 62 of the guide pad 32 has a groove shape as shown in FIG. 5, but a stepped portion 82 is formed on one groove side surface 80 of the mounting seat 62 as shown in FIG. Thus, the width of the groove is wider in the vicinity of the opening than in the vicinity of the bottom. On the other hand, as shown in FIGS. 5 and 6, a coolant groove 86 is formed on the guide pad side surface 84 opposite to the groove side surface 80 of the guide pad 32 over almost the entire length in the longitudinal direction. It faces the stepped portion 82. The coolant groove 86 is communicated with a branch coolant passage 90 in the tool body 34 by a coolant passage 88 formed inside the guide pad 32 and an elongated hole 72 of the adjustment wedge 74, and the branch coolant passage 90 is connected to the main coolant. It communicates with the passage 92. The other guide pads 32 and their coolant passages are configured in the same manner, and the main coolant passage 92 further includes a branch coolant passage 94 that opens near the cutting edge 30 of the mounting seat 42 as shown in FIG. Communicate. After all, the branch coolant passage 90 and the branch coolant passage 94 are connected to the main coolant passage 92 by three branches, and the branch coolant passage of the second stage processed portion 26 is also connected. However, the cross-sectional area of the main coolant passage 92 is larger than the sum of the cross-sectional areas of all the branch coolant passages, and the internal pressure of the main coolant passage 92 acts on all the branch coolant passages as they are. The cross sectional area of the coolant passage 88 of the guide pad 32, the cross sectional area of the coolant groove 86, and the opening area of the elongated gap (referred to as the coolant jet 96) between the stepped portion 82 and the side surface of the guide pad 32 are as follows. The order of description is smaller in later order. Therefore, the internal pressure of the main coolant passage 92 acts on the coolant outlet 96 almost as it is, and the coolant is ejected vigorously.

  The guide pad side surface 84 may be a single plane as shown in FIG. 7A, but as shown in FIG. 7B, the stepped portion is located at the same radial position as the outer peripheral surface of the tool body 34. It is desirable to provide 98. The inventor has experimented with both the configuration of FIG. 7 (a) and the configuration of FIG. 7 (b), but in the former configuration, although rare, fine chips 100 enter the coolant jet 96. In contrast, in the latter form, it has been found that the occurrence of such a situation is well avoided.

  The guide pad 32 includes a base portion 102 that is a portion where the coolant groove 86 and the coolant passage 88 are formed, and a sliding contact portion 104 that is in sliding contact with the inner peripheral surface of the small diameter portion 10. The base portion 102 is made of carbon steel. However, the sliding contact portion 104 is made of cemented carbide, and the sliding contact surface 106, which is the surface, is coated with diamond-like carbon. Diamond-like carbon is excellent in wear resistance and welding resistance and has a small friction coefficient, so that it is possible to satisfactorily prevent the workpiece from being wrinkled.

  As is apparent from FIGS. 2 and 4, the second stage processing unit 26 includes three cutting edges 110 and 112. The cutting blade 110 cuts the inner peripheral surface of the large-diameter portion 12 and the shoulder surface 14, and the cutting blade 112 forms the chamfer 17 by cutting. The cutting blade 110 is formed by a cutting tip 116 that is detachably attached to the cartridge 114, and the cutting blade 112 is formed by a cutting tip 120 that is detachably attached to the cartridge 118. An adjusting mechanism 122 is provided between the cutting tip 116 and the cartridge 114 to adjust the radial position of the cutting blade 110, and the adjusting mechanisms 124 and 126 are respectively provided between the cartridge 114 and 118 and the tool body 34. Is provided to adjust the axial position of the cutting blades 110 and 112. Since this point is the same as that of the cutting edge 30 in the first stage machining section 24, detailed description is omitted. However, the adjustment mechanism 122 of the cutting tip 116 is a parallel movement type and is accompanied by adjustment of the radial position. Thus, the inclination of the cutting blade 110 is not changed.

The stepped pilot hole 2 shown in FIG. 8 is cut into the stepped finished hole 4 by the cutting tool 20 having the above configuration.
First, finishing of the inner peripheral surface 130 of the small diameter portion 10 is started by the first step processing portion 24. As described above, since the cutting blade 30 is positioned slightly on the tip side of the cutting tool 20 from the guide pad 32, at the moment when the cutting blade 30 starts cutting the inner peripheral surface 130, The guide pad 32 does not contact the inner peripheral surface 130, but if the inner peripheral surface 130 is slightly formed, the tip of the guide pad 32 starts sliding contact with the inner peripheral surface 130, and thereafter the guide pad 32 The finishing process of the inner peripheral surface 130 is performed while the first stage processing unit 24 is guided. Eventually, the cutting blade 30 comes out from the small diameter portion 10 to a position corresponding to the chamfer 8, and finishing of the small diameter portion 10 is completed.

Subsequently, finishing of the inner peripheral surface 132 of the large-diameter portion 12 by the cutting blade 110 of the second stage processing portion 26 is started. Although no guide pad is provided in the second step processed portion 26, the guide pad 32 of the first step processed portion 24 is also used for the inner peripheral surface 130 of the small diameter portion 10 when finishing the inner peripheral surface 132 with the cutting blade 110. Therefore, the cutting tool 20 and the second stage processing unit 26 are continuously guided. Eventually, the shoulder surface 14 and the blank 16 are finished by the cutting blade 110, and after being advanced to a predetermined position, the cutting tool 20 is retracted. As described above, when the processing of the inner peripheral surface 130 of the small-diameter portion 10 is started, the guide function of the guide pad 32 is insufficient, and thus the dimensional accuracy of the inner peripheral surface 130 of the portion is not always sufficient. However, this part is conveniently removed by cutting the shoulder surface 14.
At the final stage of finishing of the inner peripheral surface 132 of the large diameter portion 12, the chamfer 17 is formed by the cutting blade 112, and the cutting of the stepped pilot hole 2 into the stepped finishing hole 4 is completed.

  Finishing is performed as described above, but the stepped pilot hole 2 is formed by casting, so the dimensional accuracy is not high, and irregular irregularities exist on the inner peripheral surface, As shown in FIG. 8 (a), recesses 18 functioning as lubrication grooves are provided at two locations separated in the diametrical direction of the inner peripheral surface of the small diameter portion 10, and the inner peripheral surface and the shoulder surface of the large diameter portion 12. Concave portions 19 functioning as lubrication grooves are formed at two locations separated from each other in the diameter direction. And the recessed part 18 and the recessed part 19 mutually differ in the 90 degree formation position. For this reason, the cutting resistance acting on each of the cutting blades 30, 110, 112 of the cutting tool 20 fluctuates drastically. However, in the first-stage machining section 24 and the second-stage machining section 26, three cutting edges are used. Since the blades 30, 110, and 112 are arranged at equal angular intervals of 120 °, the radial component of the cutting resistance of each cutting blade is well balanced, and a bending moment is less likely to act on the cutting tool 20. . In addition, when processing is performed by the first processing unit 24 as well as when processing is performed by the second step processing unit 26, the first step processing unit 24 is provided with three angular intervals of 120 °. Since the guide pad 32 is in sliding contact with the inner peripheral surface 130 of the small-diameter portion 10 of the stepped finishing hole 4 to guide the cutting tool 20, the radial displacement of the cutting tool 20 is well prevented and high machining accuracy is obtained. It is done.

  Further, the guide pad side surface 84 of the guide pad 32 is a front surface of the guide pad which is a front surface in the rotational direction of the cutting tool 20, and the coolant jet 96 (see FIGS. 5 and 5) along the guide pad side surface 84. 7) is formed, and the coolant is ejected vigorously toward the inner peripheral surface 130 of the small-diameter portion 10. As apparent from FIG. 6, the guide pad 32 is slightly protruded in the axial direction from the front end surface 140 of the tool main body 34, so that the coolant outlet 96 is shorter than the guide pad 32, but the stepped portion Since 82 is formed up to the front end surface 140 of the tool main body 34, the coolant outlet 96 is also opened on the front end surface 140 side of the tool main body 34, and the coolant is also ejected from this opening. On the other hand, the coolant groove 86 is not formed up to the end surface of the guide pad 32 opposite to the tip surface 140 side, but the stepped portion 82 is formed over the entire groove side surface 80, so that the coolant jet port is formed. 96 is formed to the end surface of the guide pad 32 opposite to the front end surface 140 side. Eventually, the coolant jet 96 is formed substantially over the entire length of the guide pad 32, and the gap between the sliding contact surface 106 of the guide pad 32 and the inner peripheral surface 130 of the small diameter portion 10 is ignored. The coolant jetted from the coolant jet port 96 flows in the direction away from the guide pad side surface 84 over the entire length of the guide pad 32 and pushes the chips away from the guide pad 32, and the sliding contact surface 106 and the small diameter portion 10. It is prevented from being bitten between the inner peripheral surface 130 of the two.

  In addition, in this embodiment, since the stepped portion 98 is formed on the side surface 84 of the guide pad, even if there is a chip 100 that faces the guide pad 32 against the flow of the coolant, As shown in FIG. 7 (b), the chip 100 abuts against the stepped portion 98, and is well prevented from entering the coolant outlet 96 formed between the guide pad side surface 84 and the groove side surface 80. If the stepped portion 98 is not provided, the chips 100 may be guided by the guide pad side face 84 and enter the coolant jet 96 as shown in FIG. If the stepped portion 98 is provided, the chips 100 guided to the guide pad side surface 84 and directed to the coolant jet 96 abut against the stepped portion 98 and are prevented from entering the coolant jet 96. .

In addition, in the above-described embodiment, the cutting blades 30, 110, 112 and the guide pad 32 are provided at three equal angular intervals, so that the cutting blades 30, 110, 112 or the guide pad 32 are provided. Are not simultaneously opposed to the two recesses 18 and 19 for the lubricating groove formed at diametrically separated positions, and a significant imbalance of the radial component of the cutting resistance occurs, or the guide It is avoided that the guide function of the pad is significantly impaired.
However, it is not essential that three cutting blades 30, 110, 112 and three guide pads 32 are provided. At least one of the cutting blades 30, 110 and the guide pad 32 can be provided in four or more. Only one blade 112 may be provided.

  Moreover, although the cutting tool 20 was provided with the 1st step process part 24 and the 2nd step process part 26, and was supposed to finish the step prepared hole 2 to the step finish hole 4, the 2nd step process part It is not essential to have 26. Further, in the first step machining unit 24 and the second step machining unit 26, three cutting blades 30 and three cutting blades 110 are provided, but the numbers of the cutting blades 30 and the cutting blades 110 are different from each other. It is also possible to

Further, in the cutting tool 20, the radial positions of the cutting blade 30 and the guide pad 32 of the first step processing portion 24 and the cutting blade 110 and the cutting blade 112 of the second step processing portion 26 can be adjusted. Therefore, it is possible to use these adjustment mechanisms in a special method for improving processing accuracy. The method will be described with reference to FIG.
First, in a free state where no force is applied to the cutting tool 20, the radial positions of the cutting blade 30 and the guide pad 32 are exaggerated and shown in FIG. The diameter of the guide pad 32 represented by G2 that is the largest in diameter (for example, 56.02 mm) and separated from the cutting edge 30 in the diametrical direction has the smallest diameter (for example, 55.98 mm), and the cutting edge in the circumferential direction. The diameter of the turning trajectory circle of the guide pad 32 represented by G1 and G3 located on both sides of 30 is adjusted to be an intermediate size (for example, 56.00 mm).

  When the cutting tool 20 adjusted in this way is advanced to enter the pilot hole 2 from the free end side and the intermediate finishing process is performed, as shown in FIG. The guide pad G3 is in a state of being separated from the inner peripheral surface 130 of the semifinished hole. Further, when the cutting tool 20 is moved backward to perform the finishing process, as shown in FIG. 9 (c), the cutting blade 30 and the tool holding device that holds the cutting tool 20 can be ignored in a state where the deflection can be ignored. The inner peripheral surface 130 of the finished hole is cut to a diameter of 56.02 and all the guide pads G1, G2, G3 are separated from the inner peripheral surface 130 of the finished hole. The reason will be described below with reference to the movement image diagram of the guide pad G1 shown in FIG.

  In FIG. 10, the arc indicated by the two-dot chain line indicates the turning trajectory circle at the most distal portion in the radial direction of the cutting blade 30 in the no-load state, and the guide pad G1 is at the position indicated by the two-dot chain line in the same no-load state. . In the state where the cutting blade 30 cuts the small diameter portion of the stepped pilot hole 2, the cutting tool 20 and the tool holding device are bent by the cutting resistance, so that the guide pad G1 is displaced in the direction of the arrow E, At the position shown by the thin line in FIG. The inner peripheral surface of the hole can be regarded as being formed by the cutting blade 30 displaced by the Y-direction component shown in FIG. 9B of the cutting resistance, and the inner diameter is the turning of the cutting blade 30 in an unloaded state. It is smaller than the diameter of the locus circle. If the guide pad G1 contacts the inner peripheral surface 130 of the hole, the X-direction component shown in FIG. 9B of the cutting resistance is converted into a Y-direction component by the effect of the slope of the inner peripheral surface, and the cutting is performed. Although the deflection of the tool 20 in the Y direction increases, the deflection in this direction is restricted by the guide pad G2 spaced in the diameter direction from the cutting edge 30 coming into contact with the inner peripheral surface of the hole. Thereby, the turning trajectory circle of the cutting blade 30 is further reduced, and the guide pad G1 is eventually displaced in the direction indicated by the arrow J and stabilized at the position indicated by the solid line. The relationship between the deflection direction and size of the cutting tool 20 caused by the cutting resistance of the cutting blade 30 and the circumferential and radial positions of the guide pads G1 and G2 allows the above phenomenon to occur. As long as the guide pads G1 and G2 slide on the inner peripheral surface of the semifinished hole formed by the cutting blade 30, the intermediate finishing of the small diameter portion 10 of the stepped pilot hole 2 is performed. The inner diameter of the semi-finished hole is the diameter 56.00 of the turning locus circle of the guide pads G1 and G2 when the cutting tool 20 is bent as described above. The diameter 56.00 and the diameter 55.98 of the turning locus circle of the guide pad G2 are determined in consideration of this.

If the intermediate finishing of the small diameter portion 10 proceeds in the above state, and the cutting blade 30 finally protrudes from the end of the small diameter portion 10 opposite to the large diameter portion 12 side, the deflection of the cutting tool 20 is eliminated, and FIG. As shown in (c), the cutting edge 30 draws a turning locus circle in an unloaded state. In this state, not only the guide pads G1 and G3 but also the guide pad G2 are separated from the inner peripheral surface 130 of the finishing hole.
In this state, the cutting tool 20 is retracted, and the cutting blade 30 eventually cuts the inner peripheral surface 130 of the semi-finished hole. However, since the machining allowance is small, the cutting resistance is small and the cutting tool is small. The deflection of 20 can be negligibly small, and the diameter of the finished hole (the diameter of the small diameter portion 10) is substantially equal to the diameter of the turning locus circle of the cutting blade 30 in an unloaded state.

  As mentioned above, although the process of the small diameter part 10 of the stepped pilot hole 2 was demonstrated, the same effect can be acquired also in the 2nd step processed part 26. FIG. That is, out of the three cutting blades 110, one of the three guide pads 32 positioned between two adjacent ones in the circumferential direction is to be cut, and the other two are set to radial positions where no cutting is performed. If adjusted, the guide pad 32 is provided in the first step processing portion 24, but functions in the same manner as in the processing by the first step processing portion 24 when processing by the second step processing portion 26. Can be made. Even during intermediate finishing with one cutting edge 110, the deflection of the cutting tool 20 is restricted to a minute amount by the guide pad 32 (G1, G2) of the first stage processing portion 24, and the bending of the cutting tool 20 during finishing processing. Therefore, the same effect as in the intermediate finishing and finishing by the first stage processing unit 24 can be obtained with respect to the intermediate finishing and finishing by the second stage processing unit 26.

2: Stepped pilot hole 4: Stepped finishing hole 10: Small diameter part 12: Large diameter part 14: Shoulder surface 20: Cutting tool 22: Taper shank 24: First step processed part 26: Second step processed part 30: Cut Blade 32: Guide pad 34: Tool body 36: Cartridge 38: Cutting tip 46: Adjustment piece 48: Guide groove 50: Adjustment piece 52: Adjustment screw 54: Adjustment screw 62: Mounting seat 64: Adjustment wedge 66: Female screw hole 68: Adjustment screw 70: Notch 80: Groove side surface 82: Stepped portion 84: Guide pad side surface 86: Coolant groove 96: Coolant outlet 98: Stepped portion 100: Chip 106: Sliding contact surface 110: Cutting blade 112: Cutting blade 114 : Cartridge 116: Cutting tip 118: Cartridge 120: Cutting tip 12 2: Adjustment mechanism 124: Adjustment mechanism 126: Adjustment mechanism 130: Inner peripheral surface 132: Inner peripheral surface

Claims (7)

A prepared hole finishing tool that is held in a cantilevered manner in a tool holding device in a held part, and that cuts an inner peripheral surface of a prepared hole in a cutting part,
The cutting portion is
Three or more cutting edges provided as equiangularly as possible on the outer periphery of the tool body;
The tool body is provided on the outer periphery of the tool body at an equiangular interval as much as possible in the axial direction, and is provided on the held portion side of each of the cutting blades with respect to the axial direction. Three or more guide pads that are in sliding contact with the inner peripheral surface of the finishing hole formed by cutting and guide the cutting portion with respect to the finishing hole;
Each of the three or more guide pads extends continuously along the front surface, which is a front-facing surface in the direction of relative rotation with respect to the finish hole of the pilot hole finishing tool, and over substantially the entire length of each guide pad. A pilot hole finishing machining tool, comprising: a coolant outlet that is provided in a state, and jets coolant toward an inner peripheral surface of the finish hole.   Guide pad holding grooves having a quadrangular cross section and extending in the axial direction are formed at three or more positions at equal angular intervals on the outer peripheral surface of the tool body, and the three or more guides are provided in each of the guide pad holding grooves. 2. The pilot hole finishing tool according to claim 1, wherein each of the pads is held, and the coolant jet is formed between the front surface of the guide pads and a groove side surface of the guide pad holding groove facing the front surfaces.   The portion of the front surface of the guide pad that is radially outward from the same radial position as the outer peripheral surface of the tool body is retracted with respect to the direction of relative rotation with respect to the finishing hole of the finishing tool with respect to the radially inner portion. The prepared hole finishing tool according to claim 2, wherein a stepped portion extending over the entire length of the guide pad is formed.   Guide pad holding grooves having a quadrangular cross section and extending in the axial direction are formed at three or more positions at equal angular intervals on the outer peripheral surface of the tool body, and the three or more guides are provided in each of the guide pad holding grooves. Each of the pads is held, and at least one of the bottom surfaces of the guide pad holding groove and the guide pad facing each other is inclined with respect to the axial direction of the tool body, so that the thickness between the two bottom surfaces is increased. A linearly changing gap is formed, and an adjustment wedge is disposed in the gap, and the adjustment wedge is moved along the guide pad holding groove between the adjustment wedge and the tool body. A guide pad radial position adjusting mechanism is provided for adjusting the radial position of the sliding contact surface that is in sliding contact with the inner peripheral surface of the pilot hole by parallel movement of the guide pad; Prepared hole finishing tool according to any one of the guide pad sandwiching adjustment wedge state claims 1 and fixed by tightening the fastening screw on the bottom surface of the guide pad holding groove 3.   A cutting tip radial position in which each of the three or more cutting edges is formed by a cutting tip movable relative to the tool body, and a radial position of each of the cutting tips with respect to the tool body is adjusted. The prepared hole finishing tool according to any one of claims 1 to 4, comprising an adjusting mechanism.   An axial position adjustment mechanism that adjusts an axial position of at least one of the three or more cutting blades and the three or more guide pads with respect to at least one of the tool bodies. The prepared hole finishing tool according to any one of 1 to 5.   The prepared hole finishing tool according to any one of claims 1 to 6, wherein a diamond-like coating is applied to a sliding contact surface that is in sliding contact with an inner peripheral surface of the finishing hole of the guide pad.

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