JP2007021646A - Tip holder exchange type drilling tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reamer suitable for machining a large hole used for a valve body or an oil pump at high speed rotation, at high feed and with high accuracy. <P>SOLUTION: This tip holder exchange type drilling tool is a tip holder exchange type reamer including: a shaft-like tool body 1 having a taper part which becomes gradually smaller in as it goes toward one end; a tip holder 2 having a taper hole 21 fitted to the taper part 12; a holder pusher 3 moved toward the tip of the tool body 1 to loosen engagement of the tip holder 2 and the tool body 1; and a tip 7 fixed to the tip holder 2. The holder pusher 3 is rotated in relative to the tool body 1 to move in the direction of shaft center, thereby pushing out the chip holder 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a drilling tool, and more particularly to a large-diameter drilling tool using a cemented carbide, polycrystalline diamond, or CBN sintered body as a cutting edge.

  Examples of drilling tools include drills and reamers. Of these, the reamer is a tool for obtaining a smooth finished surface as well as an accurate diameter. If the rotational speed and feed are increased in order to increase the machining efficiency of such a tool, chatter and runout occur and the machined surface accuracy deteriorates. In particular, when the feed rate is increased, a feed mark is generated, the accuracy of the hole diameter is deteriorated, and in the worst case, the cutting edge may be missing.

  The invention described in Patent Document 1 relates to a reamer in which straight blades and inclined blades are alternately provided at one end of an axial tool body. The inclined blade is located behind the straight blade, which is the base side, and the outer peripheral tip of the inclined blade has a larger outer diameter than the outer peripheral tip of the straight blade, and this portion performs the burnishing action. This makes it possible to enhance the burnishing effect by the fact that the inclined blade performs an oblique cutting and plays a brooch-like role and the contact of the circumferential portion with the work hole. The straight blade is brazed to the tool body.

The invention described in Patent Document 2 relates to a throw-away reamer, and is a type of reamer that replaces only the cutting edge tip when the cutting edge tip is worn. This reamer has a structure in which a cutting edge tip is directly pressed against a tool main body with a holding piece, and the cutting edge tip can be exchanged by removing the holding piece.
Japanese Utility Model Publication No. 55-75417 JP 2003-117725 A

  However, in the reamer of Patent Document 1 in which the tip is brazed directly to the tool body, the entire expensive tool becomes a lifetime when the tip becomes a lifetime due to wear or the like, which is uneconomical.

  Further, according to the reamer described in Patent Document 1, two inclined blades and two straight blades each made of cemented carbide are attached to the main body. At that time, the core blur between the four chips must also be reduced. However, if the number of chips is large, the core blur between chips increases, which affects the processing accuracy.

  On the other hand, although the tip exchange type reamer described in Patent Document 2 that holds the tip using a mechanism such as screw tightening or clamping can replace only the tip, it can be used for a high-speed, high-feed hole drilling tool. There wasn't. This is because the mechanical strength of the chip holding mechanism is weaker than the cutting resistance received by the chip, and the chip mounting accuracy deteriorates with repeated use and cannot be used. Probably, it is presumed that during use, the holding mechanism is deformed in the order of μm, and core blurring occurs.

  An object of the present invention is to provide an inexpensive tool for exchanging a tip holder replacement type that is suitable for use at high speed rotation and high feed and can be machined with high accuracy.

  According to the present invention, the outer diameter of the taper portion is reduced in the axial direction of the tool main body, the tip holder having a taper hole fitted to the taper portion, and the axial direction of the tool main body. The tool pusher that moves in the direction to loosen the fit between the tip holder and the tool body, and the tool holder moves in the direction in which the outer diameter of the taper portion increases in the axial direction of the tool body, It is a tool for exchanging a chip holder exchanging type having a holder pushing tool for tightening and a chip fixed to the chip holder.

  In a drilling tool used under severe cutting conditions, the force applied to the tip is large, and it is necessary to maintain high rigidity of the tool body and the tip. Since high accuracy is also required at the same time, it is necessary that the core blur is small. As a result of various examinations on mounting methods that satisfy such conditions, the problem can be solved by adopting a shaft-shaped tool body having a tapered portion with a tapered tip and a tip holder having a tapered hole that fits the tapered portion. I understood. By fitting the tapered portion and the tapered hole, the tool main body and the tip holder can be concentrically and firmly fixed. Therefore, in the present invention, a conical taper surface is formed on a part of the outer peripheral surface of the tool body, the portion having the taper surface is used as a taper portion, and the inner surface of the tool body insertion hole of the tip holder is formed into a conical taper. A hole. Among these conical tapers, when fitted with a Jacobs taper described in JIS 0612 or the like, the rigidity is higher and the core blur is smaller.

  Here, it is necessary to form the taper part provided in the tool main body so that the outer diameter becomes smaller toward the distal end side direction of the tool main body. By doing in this way, since the reaction force received from a work material in the case of a hole process acts in the direction which narrows fitting with a tool main body and a tip holder, a tip holder does not remove | deviate from a tool main body. Further, since the force acting on the chip holder is received by the entire taper portion of the tool body through the taper hole of the chip holder, the core blur hardly occurs even under high feed conditions, and stable cutting can be performed. .

  Further, various factors for the core blur accuracy were also examined, and it was found that there was a limit to increase the core blur accuracy when many chips were used. That is, the accuracy of the reamer is determined by the largest value of the core blur of each chip. Therefore, from the viewpoint of reducing the core blur, it is preferable to use one chip rather than using a plurality of chips.

  The holder pusher is configured to loosen the fitting between the tip holder and the tool body by moving the tool pusher in a direction in which the outer diameter of the tapered portion is reduced in the axial direction of the tool body. Such a configuration for loosening the fitting between the tip holder and the tool body is preferable because it is simple to apply screw coupling. As a specific example, the holder pusher is a nut having a female screw, a male screw is formed on the outer peripheral surface of the tool body, the holder pusher is rotated relative to the tool body and moved in the axial direction, and the chip holder Is pressed with a holder pusher to release the fitting between the tapered portion and the tapered hole.

  Since the tool of the present invention is mainly intended for drilling under severe cutting conditions, the pressing pressure of the tool on the workpiece is very high. For this reason, the chip holder bites into the tool body, and it becomes difficult to remove the chip holder from the tool body.

  As described above, by attaching the chip holder and the holder pusher to the tool body, screwing the holder pusher and the tool body, and rotating the holder pusher relative to the tool body, the holder pusher The tip holder can be easily removed by moving it toward the tip of the tool body. Thereby, in the removal operation | work of a chip holder, it does not cause a deformation | transformation in a tool main body, but it can be set as a long-life tool main body. However, since the tool body and the holder pusher are firmly screw-coupled, it is desirable that the outer peripheral surface be roughened so that the holder pusher can be easily rotated relative to the tool body. For example, knurling is performed on the outer peripheral surface of a nut-shaped holder pushing tool, or a hole or groove is provided on the surface of the holder pushing tool, and a rotation assisting tool such as a handle is inserted into the hole or groove and rotated. There are methods.

  On the other hand, the holder pushing tool is configured to reduce the fitting between the tip holder and the tool body by moving in the direction in which the outer diameter of the tapered portion increases in the axial direction of the tool body.

  Here, when the drilling tool of the present invention is used as a reamer for finishing the inner surface of the through-hole, a protrusion having a male thread formed at the tip of the tool body is provided, and after the tip holder is installed on the tool body, the protrusion It is preferable that the nut-shaped holder pusher having a female screw formed on the part is formed into a shape to be screw-coupled. By doing in this way, a chip holder can be firmly fixed to a tool main body only by narrowing down a holder pushing tool in a tool main body. Furthermore, when the holder pusher is fixed to the protruding portion, the holder pusher is formed on the workpiece by configuring the holder pusher so that the outer diameter of the holder pusher is smaller than the maximum outer diameter of the tip holder to which the cutting blade is attached. It is preferable that the through hole is not damaged by contact with the through hole. When the hole machining tool of the present invention is used as an inner surface finishing reamer for a blind hole (non-through hole), a female screw hole is provided in the tip end surface of the tool body, and the female screw hole has a male screw and a head. If the shape is such that the T-shaped holder pusher is fixed, the holder pusher can be prevented from protruding from the tip surface of the tip holder at the tip of the tool. Furthermore, by having such a structure, the head of the holder pusher can be prevented from being stopped against the bottom of the blind hole, so that an unprocessed portion is generated on the inner surface near the bottom of the blind hole. There is nothing.

  The chip is preferably plate-shaped. The chip used in the present invention is a cemented carbide or a thin polycrystalline diamond sintered body or a thin cubic boron nitride sintered body formed on a cemented carbide. These materials are generally plate-shaped.

  2A and 2B, which will be described later, describe an example of a straight blade having a cutting edge along the tool axis. However, the cutting edge is inclined with respect to the tool axis. An inclined blade may be used. If an inclined blade is used, there is an effect that the cutting resistance is reduced.

  In addition, it is desirable to provide a margin on the flank face of the chip. It is advantageous to provide a margin for ensuring the accuracy of the finished surface to be processed.

By adopting the configuration of the present invention, when the chip is damaged or worn, only the chip holder can be exchanged, so that it can be an economical tool and has the following effects.
[1] Since the tool body and the tip holder are fitted with a tapered surface, the tip holder can be accurately and easily fixed concentrically to the tool body.
[2] The tip holder can be easily attached to and detached from the tool body by the holder insertion / extrusion tool.
[3] When the tip holder is attached to or detached from the tool body by the holder push-in tool or push-out tool, the tool body and the tip holder are not deformed or damaged.

<Example 1>
In this example, an inner surface finishing reamer for through holes will be described with reference to FIGS.

  FIG. 1 is a cross-sectional view of a holder exchange type reamer according to the present invention. The reamer of this example includes a shaft-shaped tool body 1 having a tapered portion on the tip side, a tip holder 2 fitted to the tapered portion of the body 1, a holder pusher 3 for removing the tip holder 2, And a holder pusher 4 for firmly fitting the chip holder 2 to the main body 1.

  As the tool body 1, an SCM35 steel bar having a total length of 150 mm and a diameter of 25 mm was used. An M12 male screw 11 was formed at the tip of the tool body 1. Next, a conical taper 12 having a Jacobs taper No. 6 conical taper (JIS B-0612) and a maximum outer diameter of 17.2 mm was formed adjacent to the base side of the male screw 11. The conical taper 12 has a diameter that decreases toward the tip of the tool. Further, an M20 male screw 13 was machined on the base side of the conical taper 12. Here, the conical taper 12 and the part of the tool body 1 other than the taper 12 were formed coaxially. In this example, the portion where the conical taper 12 is formed is a tapered portion.

  Next, the chip holder 2 will be described with reference to FIG. FIG. 2 (A) is a perspective view of the chip holder, and FIG. 2 (B) is a plan view thereof. The tip holder 2 has a short hollow cylindrical shape, and has a tapered hole 21 whose inner peripheral surface is a tapered surface adapted to the conical taper 12. The tapered hole 21 and the outer circumference of the chip holder 2 were formed coaxially. On the other hand, a cutout extending in the axial direction is formed on the outer peripheral surface of the chip holder 2. Due to the notches, a parallel surface 22 parallel to the radial direction of the chip holder 2 and an orthogonal surface 23 orthogonal to the parallel surface 22 are exposed to the chip holder 2. A chip 7 is attached in parallel to the axis of the chip holder 2 on the upper end side of the notch.

  This chip 7 is composed of two layers of a diamond sintered body 71 and a cemented carbide 72. The front surface side of the chip 7 is composed of a diamond sintered body 71, and the joint surface side with the parallel surface 22 of the chip holder 2 is composed of a cemented carbide 72. Here, the bottom surface made of the cemented carbide 72 of the chip 7 is brazed to the parallel surface 22 parallel to the radial direction, and one side surface of the chip 7 where the boundary between the diamond sintered body 71 and the cemented carbide 72 appears is shown. It brazed and fixed to the orthogonal plane 23 which is orthogonal to the above. The surface of the diamond sintered body 71 becomes a rake face 8. A ridge line formed by the rake face 8 and the other side face of the chip 7 becomes the outer peripheral cutting edge 9. The outer peripheral cutting edge 9 protrudes slightly from the outer peripheral edge of the cylindrical member that holds the chip 7 in the chip holder 2.

  In this example, the hole drilling tool is formed when the tool body 1 and the tip holder 2 are formed as described above, so that the conical taper 12 of the tool body 1 and the taper hole 21 of the tip holder 2 are fitted. The main body 1 and the chip holder 2 can be held concentrically. That is, the center of the circle drawn by the tip of the tip 7 attached to the outer periphery of the tip holder 2 when the tool body 1 (tip holder 2) is rotated and the tool axis 10 can be matched.

  On the other hand, the holder pusher 3 is nut-shaped as shown in FIG. On the inner periphery of the holder pusher 3, an M20 female screw 31 that is screw-coupled to the male screw 13 of the tool body 1 is formed. Further, on the outer peripheral surface of the pusher 3, rotation grooves 32 are formed at four positions at equal intervals. This pusher 3 is for removing the tip holder 2 fitted to the conical taper 12 of the tool body 1 without damaging the tool body 1 or the tip holder 2.

  Further, the holder pushing tool 4 shown in FIG. 1 is nut-shaped. The holder pusher 4 has an M12 female screw 41 that is screwed to the male screw 11 of the main body 1.

These components are combined as follows.
First, the M20 male screw 13 is screwed into the tool body 1 while rotating the holder pusher 3.

  Next, the tip holder 2 (FIG. 2A) is fitted into the conical taper 12 of the tool body 1.

  Further, the holder pusher 4 is screwed into the male screw 11 of the tool body 1 to press the end surface 25 of the chip holder 2 so that the inner peripheral surface of the tapered hole 21 of the chip holder 2 presses the outer peripheral surface of the conical taper 12. Then, the tip holder 2 is firmly fixed to the tool body 1 (so that the tapered hole 21 of the holder 2 and the conical taper 12 of the tool body 1 are fitted).

  As a result, the tip holder 2 is pressed against the base side of the tool body 1 with the end face of the holder pusher 4 and firmly fixed.

Next, a procedure for replacing the chip 7 will be described.
First, the holder pusher 4 is removed from the tool body 1.
Next, a claw of a removal handle (not shown) is fitted in the rotation groove 32 of the holder pusher 3, and the handle pusher is rotated to rotate the holder pusher 3. Thereby, if the holder pushing tool 3 is moved to the tip side of the tool body 1, the tip holder 2 can be pushed out by the end face of the holder pushing tool 3, and the holder 2 can be easily removed. Thereby, the chip 7 is exchanged together with the chip holder 2.

  Since the tool in this example is a tool for high-speed drilling, the tip 7 (tip holder 2) is strongly pressed in the direction of the axis 10 of the tool body 1 by the work material. Furthermore, since the tip holder 2 is pressed from the tip side by the work material, the tool body 1 and the tip holder 2 are more firmly fitted. Without the holder pusher 3, it was difficult to remove the tip holder 2 from the tool body 1. For example, in FIG. 1, the male screw 11 at the tip is struck with a hammer, and by this impact, the fitting between the tapered hole 21 of the tip holder 2 and the conical taper 12 of the tool body 1 is loosened to remove the holder 2 and insert the tip 7 Can be replaced. In that case, the struck male screw 11 is crushed and becomes unusable, and the life of the tool body 1 is shortened. In this example, by using the holder pusher 3 that is screw-coupled to the main body 1, the chip holder 2 can be removed without damaging the tool main body 1 and the chip holder 2.

<Example 2>
Next, a reamer for finishing the inner surface of the blind hole (non-through hole) formed so that the distal end portion of the pushing tool does not protrude from the end surface of the chip holder will be described with reference to FIG.

  FIG. 4 is a sectional view showing another example of the holder exchange type reamer of the present invention. This reamer also includes a shaft-shaped tool body 1 having a tapered portion (conical taper 12) on the tip side, a tip holder 2 fitted to the tapered portion of the body 1, and a holder pushing tool for removing the tip holder 2. 3 and a holder pusher 4 for firmly fitting the chip holder 2 to the main body 1.

  A hole in which a female screw 14 is formed is provided at the center of the tip surface of the tool body 1. Further, a conical taper (JIS B-0612) of Jacobs taper No. 6 is formed on the outer periphery of the tip portion of the tool body 1 from the tip toward the base side. The conical taper 12 has a diameter that decreases toward the tip of the tool. Similarly to Example 1, the conical taper 12 and the part of the tool body 1 other than the taper 12 were formed coaxially. Further, a male screw 13 is formed on the base side of the conical taper 12.

  The chip holder 2 has a short hollow cylindrical shape, and has a tapered hole 21 whose inner peripheral surface is a tapered surface adapted to the conical taper 12. Here, the tapered hole 21 and the outer circumference of the chip holder 2 were formed coaxially. A concave portion 24 having an inner diameter larger than the inner diameter of the tapered hole 21 at the distal end side of the tool body 1 and the outer diameter of the head of the holder pressing tool described later is provided on the distal end side of the tapered hole 21. It is possible to hold the head of the holder push-in tool 4 on the head. The shape of the part to which the chip 7 is attached, how to attach it, and the chip 7 are the same as in the reamer of the first embodiment.

  The holder pusher 3 is also nut-like, similar to the reamer in FIG. The holder pusher 4 is a bolt-shaped member having a T-shaped cross section having a head portion and a male screw portion (a shaft portion having a male screw 42). The male screw 42 is formed so as to be screwed into the female screw 14 provided at the center of the tip of the tool body 1. Further, as described above, since the head of the pusher 4 can be held against the recess 24 of the chip holder 2, the holder pusher 4 is rotated while the female screw 14 of the tool body 1 is rotated. When screwed, the head of the holder pusher 4 comes into contact with the recess 24 of the chip holder 2, and the chip holder 2 can be pressed in the root direction of the tool body 1. In this example, in order to rotate the holder pusher 4, a narrowed tool fitting hole 43 is provided in the head of the pusher 4, and a hexagon wrench or the like is inserted into the fitting hole 43 so that the holder pusher 4 is Rotate. Here, in order to securely fix the tip holder 2 to the tool body 1, the axial length of the tapered surface in the tapered hole 21 provided in the inner peripheral surface of the tip holder 2 is set to the outer periphery of the tip portion of the tool body 1. It was longer than the axial length of the conical taper 12 provided. Further, the axial length of the chip holder 2 was adjusted so that the holder pressing tool 4 could be screwed to fix the chip holder 2 sufficiently firmly.

These components are combined as follows.
First, the tool pusher 3 is screwed into the tool body 1 while rotating the holder pusher 3 into the male screw 13 of M20.

  Next, the tip holder 2 is fitted into the conical taper 12 of the tool body 1.

  Further, the holder holder 4 is screwed into the female screw 14 of the tool body 1 so that the inner peripheral surface of the tapered hole 21 of the tip holder 2 presses the outer peripheral surface of the conical taper 12, and the tip holder 2 is firmly attached to the tool main body 1. And fix.

  As a result, the concave portion 24 of the tip holder 2 is pressed against the base side of the tool body 1 at the head portion of the holder pusher 4 and firmly fixed.

  The procedure for exchanging the tip 7 is performed by removing the holder pusher 4 and turning the holder pusher 3 to push up the tip holder 2 and remove it from the tool body 1 in the same manner as in the first embodiment.

<Test example>
Next, a cutting test was performed using the reamer shown in FIG. As the chip, a material in which a diamond sintered body was lined with a cemented carbide was used. The radius of the outer peripheral cutting edge was 15 mm, which was the same radius as the hole to be reamed. Then, a chip with a margin on the flank and a chip with no margin were prepared. As a reamer used for the cutting test as a comparative test, a chip exchange type reamer described in Patent Document 2 was used.

  The work material is an aluminum casting with a pilot hole of 29.5 mm in diameter. A hole with a diameter of 30 mm and a length of 45 mm was reamed. The holder exchange type reamer of the present invention was cut at a rotation speed of 10,000 times per minute, a cutting speed of 400 m / min, and a feed of 0.8 mm / min. Further, since the reamer described in Patent Document 2 cannot be cut under the above-described conditions, it was processed under the conditions that the number of rotations per minute was 5000, the cutting speed was 200 m / min, and the feed was 0.1 mm / min.

  In the cutting test, the tool life was determined when the surface roughness of the work material exceeded 2 μm in Rz, and the performance was evaluated based on the degree to which the work material was welded to the surface of the reamer. As a result, those having a margin width according to the present invention have a long life and can be processed with high efficiency. Further, the life of the present invention without the margin width was reduced by about 20% compared with that with the margin width, but the processing efficiency was the same. On the other hand, in the comparative example, the life was almost the same as that with the margin width of the present invention, but as can be seen from the above cutting conditions, the feed was 1/8, which is very inefficient. Only processing was possible.

  The tool for exchanging chip holders according to the present invention can be applied to a reamer. Reamers can also be used for machining large diameter holes used in valve bodies and oil pumps. In particular, it can be used in the field of machining large holes with a diameter of 8 mm or more with high rotation and high feed.

It is sectional drawing of the chip holder exchange type reamer of this invention. FIG. 2 (A) is a perspective view of the chip holder of the present invention and a chip mounted on the chip holder, and FIG. 2 (B) is a plan view of the chip holder. It is a perspective view of the holder pushing tool of the present invention. It is sectional drawing of another example of this invention chip holder exchange type reamer.

Explanation of symbols

1 Tool body
11 Male thread 12 Conical taper 13 Male thread 14 Female thread
2 Tip holder
21 Tapered hole 22 Parallel surface 23 Orthogonal surface 24 Recessed portion 25 End surface
3 Holder pusher 31 Female thread 32 Groove for rotation
4 Holder pusher 41 Female screw 42 Male screw 43 Tightening tool fitting hole
7 Chip 71 Diamond sintered body 72 Cemented carbide
8 Rake face
9 Peripheral cutting edge
10 Tool axis

Claims (4)

A shaft-shaped tool body having a tapered portion with a tapered front end side;
A chip holder having a tapered hole to be fitted to the tapered portion;
A holder pusher that moves in a direction in which the outer diameter of the taper portion decreases in the axial direction of the tool body and loosens the fit between the tip holder and the tool body;
A holder pusher that moves in a direction in which the outer diameter of the taper portion increases in the axial direction of the tool body to narrow the fit between the tip holder and the tool body;
A tool for exchanging chip holders, which has a chip fixed to the chip holder.   2. The chip holder exchanging type hole machining tool according to claim 1, wherein the holder pusher is screwed to the tool body so as to be movable in the axial direction of the tool body.   The tip holder exchanging type hole machining tool according to claim 1, wherein the holder pusher is screwed to the tool body so as to be movable in the axial direction of the tool body.   The tip holder replacement type drilling tool according to any one of claims 1 to 3, wherein a margin is provided on the flank face of the tip.

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