JP3876577B2 - Throwaway reamer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reamer for finishing a prepared hole formed in a workpiece to a predetermined inner diameter, and more specifically, a throw provided with a land having an arc-shaped outer peripheral surface on a cutting edge attached to a tip portion of a tool body. It is about Away reamer.
[0002]
[Prior art]
Conventionally, in general, a deep pilot hole drilled in a workpiece by a drill or the like, or a pilot hole H penetrating a plurality of ribs G arranged at intervals in the workpiece W as shown in FIG. Is finished to a predetermined inner diameter, a throw-away reamer 4 in which a throw-away tip 3 is attached to the tip of a long tool body 1 provided with a guide pad 2 on the outer peripheral portion 1a is used. As shown in FIG. 6, the throw-away tip 3 of the long throw-away reamer 4 has a cutting edge 5 having an acute cross-sectional shape formed by a scooping surface 5 a and a relief surface 5 b. It is formed extending in a direction parallel to the axis C.
[0003]
When finishing the prepared hole H of the workpiece W, the throw-away reamer 4 is mounted on the main spindle of the machine tool and rotated in the direction of the axis C. Then, the finishing process is sequentially advanced to the front pilot hole H2 to finish the finishing process of the frontmost pilot hole H3.
In the above, the guide pad 2 of the tool body 1 is in sliding contact with the inner periphery of the bush arranged facing the opening of the pilot hole H1 and the inner peripheral surfaces of the finished pilot holes H1 and H2. 1 is guided and supported.
[0004]
[Problems to be solved by the invention]
After finishing the preparation of the pilot hole H as described above, the throw away reamer 4 stops rotating, and the main shaft of the machine tool is retracted in the direction of the axis C, so that the throw away inserted into the pilot hole H is completed. The reamer 4 is extracted from the pilot hole H.
At that time, as shown in FIG. 5 in particular, when the throwaway reamer 4 is mounted horizontally on the horizontal main spindle of the machine tool, the throwaway is performed at a rotational position in which the cutting edge 5 of the throwaway tip 3 is directed downward. When the reamer 4 is stopped, the tool body 1 is retracted as it is to extract the throw-away reamer 4 from the pilot hole H, and the tool body 1 is bent slightly downward by its own weight. The sharp cutting edge 5 of the throw-away tip 3 passes in the direction of the axis C in a state of being in line contact with the inner peripheral surface of the bent hole H that has been bent and finished, so that the inner circumference of the finished hole H that has been finished Muscle damage occurs on the surface.
As a result, in the conventional throw-away reamer, a defective product may be generated on the workpiece.
[0005]
The present invention has been made in view of the above points, and when the throw-away reamer used for machining is extracted from the finished prepared hole after the finished machining of the prepared hole in the workpiece, However, an object of the present invention is to provide a throw-away reamer that does not cause damage to the finished prepared hole.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a throw-away reamer provided with a throw-away tip having a cutting edge projecting toward the outer peripheral side of a tool body at the tip of a substantially cylindrical tool body rotated about an axis. The flank facing the tool body outer peripheral side of the throw-away tip has an arc-shaped outer peripheral surface formed so that the radius centered on the axis gradually decreases from the cutting edge toward the rear side in the cutting rotation direction. The land is provided.
[0007]
In the throw-away reamer having the above configuration, the tool body is sent in the axial direction while rotating, and the prepared hole of the workpiece is finished by the cutting blade, but when the finishing process is finished, the tool body is rotated. After being stopped, it is retracted and extracted from the finished prepared hole.
At that time, even if the tool main body stops with the cutting edge facing downward and the tool main body is bent slightly downward, the arc-shaped outer peripheral land of the cutting edge is the inner periphery of the prepared hole after finishing. Since the surface is moved substantially in surface contact with the surface and moved in the axial direction, the inner peripheral surface of the finished prepared hole does not have a streak-like scar due to the cutting edge.
Accordingly, there is no problem that a defective product is generated on the workpiece.
[0008]
In the throw-away reamer, when the width of the land in the cutting rotation direction is set within a range of 0.01 mm to half the thickness of the throw-away tip in the cutting rotation direction, finishing is performed when the tool body is extracted. The inner peripheral surface of the prepared prepared hole does not have a streak-like scar due to the cutting blade, and the cutting resistance by the land does not increase during finishing.
[0009]
Further, in the throw-away reamer, a guide pad that protrudes toward the outer periphery of the tool body and extends in the axial direction is provided on the outer periphery of the tool body, and the radius of curvature of the arc-shaped outer periphery of the land is the same as that of the outer periphery of the guide pad. Setting the range between the turning radius around the axis and the turning radius 5 mm smaller than that can more reliably prevent streak marks on the inner peripheral surface of the finished prepared hole, while the land is finished. Since the machined pilot hole is not hit, finishing of the pilot hole with the cutting blade is performed without any trouble, and the tool body is smoothly extracted from the finished pilot hole.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
In addition, the same code | symbol is attached | subjected and demonstrated to the component same as the conventional throw away reamer 4. FIG.
A throw-away reamer 6 according to an embodiment of the present invention has a tip pocket 7 cut out in an L-shape at the tip of a tool body 1, and a rectangular flat plate on a tip mounting seat 1 c provided there. A shaped throw-away tip 8 is detachably attached by a clamp screw 9 with its cutting edge (cutting edge) 8 a protruding from the outer peripheral side of the tool body 1.
[0011]
The rotation diameter D of the cutting edge 8a around the axis C of the tool body 1 in the throw-away tip 8 is 0.002 mm to 0.008 mm from the rotation diameter D1 of the arcuate surface around the axis C of the guide pad 2, usually 0. 006 mm is set larger.
The guide pad 2 extends parallel to the axis C provided on the outer periphery of the tool body 1, and a plurality of short pad members 2 a are spliced into a plurality of concave grooves 1 b formed at intervals in the circumferential direction. And fixed to the tool body 1 by brazing.
[0012]
As shown in FIG. 3, the throwaway tip 8 has a flank 8 b facing the outer peripheral side of the tool body 1, and a cutting rotation direction T about the axis C from the cutting edge 8 a at the tip of the scooping surface 8 c. A land 8d having a circular arc surface (arc-shaped outer peripheral surface) 8e is provided toward the opposite side.
The land 8d has a center C1 on a line S connecting the axis C and the cutting edge 8a in a cross section orthogonal to the axis C of the tool body 1, and the front end side outer peripheral surface in the cutting rotation direction T is An arc surface 8e is formed on the rotation diameter D of the blade 8a, and the radius of curvature thereof, that is, the rotation radius R2 from the center C1 to the arc surface 8e is the arc surface (outer peripheral surface) of the guide pad 2. It is equal to or slightly smaller than the rotation radius R1 which is half of the rotation diameter D1 around the axis C of 2b.
That is, the land 8d is formed such that the radius around the axis C gradually decreases as the arcuate outer peripheral surface 8e moves from the cutting edge 8a toward the rear side (opposite side) of the cutting rotation direction T. ing.
[0013]
If the rotation radius R2 of the land 8d is larger than the rotation radius R1, it hits the finished prepared hole. Therefore, in order to avoid this, the rotation radius R1 should be set smaller than the upper limit value. On the other hand, if it is set too small, it is related to the width E of the land 8d, which will be described later, but the contact surface pressure of the land 8d against the prepared hole may increase when the throwaway reamer 6 is extracted from the finished prepared hole. The lower limit value is set to a rotation radius that is 5 mm smaller than the rotation radius R1 (a rotation diameter that is 10 mm smaller than the rotation diameter D1 of the guide pad 2 when the arcuate outer peripheral surface 8e of the land 8d is viewed as a rotation diameter about the axis C). Is preferred.
[0014]
The land 8d has a width E in the cutting rotation direction T set within a range of 0.01 mm to half the thickness of the throw-away tip 8 in the cutting rotation direction T. The axis of the tool body 1 It extends in a direction parallel to C and is formed over the entire length of the cutting edge 8a.
If the width E of the land 8d is larger than the above range, the area where the land 8d slides on the cutting surface at the time of cutting increases to increase the cutting resistance. If the width E is smaller than the above range, the tip of the throwaway tip 8 has an acute angle. Therefore, when the tool body 1 is pulled out from the finished prepared hole, a streak-like scar may be attached to the prepared hole. A more preferable width E of the land 8d is in a range of 0.05 mm to 0.50 mm, and is usually set to about 0.3 mm.
[0015]
The throw-away reamer 6 configured as described above is attached to the spindle of a machine tool and rotated in the tool rotation direction T around the axis C in the same manner as in the past, while moving to the tool tip side in the axis C direction. Given the feed, for example, a deep pilot hole formed in the workpiece by a gun drill or the like, or a hole in the engine cylinder head as shown in FIG. A pilot hole H that penetrates through the plurality of ribs G that are opened is finished to a predetermined inner diameter by the cutting blade 8.
[0016]
When the finishing process is completed, the rotation of the throw-away reamer 6 is stopped, and then the reamer 6 is extracted from the finished prepared hole H.
At that time, the guide pad 2 of the tool body 1 is slidably contacted with the inner peripheral surface of the finished prepared hole H to guide and support the tool body 1, and the cutting edge 8 a of the throw-away tip 8 is in strong contact with the prepared hole H. The reamer 6 is smoothly extracted from the finished prepared hole H.
[0017]
In the above description, even if the tool body 1 is stopped with the cutting edge 8a of the throw-away tip 8 facing downward and is bent slightly, the throw-away reamer 6 causes the throw The land 8d of the arcuate surface of the away tip 8 is moved in the direction of the axis C substantially in surface contact with the inner peripheral surface of the finished hole H after finishing, and the throw-away tip 3 of the throw-away tip 3 is moved like the conventional throw-away reamer 4. Since the state in which the acute-angle cutting blade 5 is in line contact with the finished prepared hole H does not occur, the surface pressure of contact with the inner peripheral surface of the finished prepared hole H can be suppressed to a small value. Therefore, the reamer 6 can be smoothly extracted from the finished prepared hole H without any streak scars.
Therefore, according to the throw away reamer 6 having the above-described configuration, it is possible to reliably prevent a defective product from being generated on the workpiece.
[0018]
In the above embodiment, the land 8d has a center on the line S connecting the axis C and the tip of the cutting edge 8a, and the axis C of the arcuate surface (outer peripheral surface) 2a of the guide pad 2. The circular arc surface 8e having a rotation radius R2 equal to or less than the rotation radius R1 half of the rotation diameter D1 is not limited to this, but as shown in FIG. An arc surface 8f having a rotation radius R2 having a center C2 at a position slightly deviating in the cutting rotation direction T from a line S connecting the tip of the cutting edge 8a may be a scooping surface on the front end side in the cutting rotation direction T. The outer peripheral position of 8c is on the rotation diameter D around the axis C of the cutting edge 8a, and the radius of curvature Rx from the axis C gradually decreases toward the rear side in the cutting rotation direction T (opposite side of the scooping surface 8c). Oval, parabolic, etc. It may be formed in an arc outer peripheral surface 8g shaped convex surface.
Even in the configuration of these lands, when the tool body 1 is pulled out in the direction of the axis C, the inner peripheral surface of the finished prepared hole is not damaged, and the same effects as those of the land of the above embodiment are obtained. Is obtained.
[0019]
【The invention's effect】
As described above, according to the first aspect of the present invention, the axis is centered on the flank facing the tool body outer peripheral side of the throw-away tip of the throw-away reamer from the cutting edge toward the rear side in the cutting rotation direction. Since the land having an arc-shaped outer peripheral surface formed so that the radius to be gradually reduced is provided, when the throw away reamer is extracted from the finished prepared hole, the cutting blade is facing downward. Even if the tool main body is stopped and the tool main body is bent slightly downward, the arc-shaped outer peripheral surface land is moved in the axial direction while being substantially in surface contact with the inner peripheral surface of the prepared hole after finishing, It is possible to prevent streak-like scars from being formed on the inner peripheral surface of the finished prepared hole.
Therefore, it is possible to reliably prevent a defective product from being generated on the workpiece.
[0020]
According to the second aspect of the present invention, the width of the land in the cutting rotation direction is set within a range of 0.01 mm to half the thickness of the throw-away tip in the cutting rotation direction. The inner surface of the prepared hole that is sometimes finished does not have streak scars caused by the cutting edge, and prevents the cutting resistance from being increased by the land during the finishing process. Processing can be performed.
[0021]
According to invention of Claim 3, while providing a guide pad in the outer peripheral part of a tool main body, the curvature radius of the arc-shaped outer peripheral surface of the land in a throw-away tip is made around the axis line of the said tool main body of the outer peripheral surface of the said guide pad. Since the range between the turning radius and the turning radius 5 mm smaller than that is set, it is possible to more surely prevent streak marks from being attached to the inner peripheral surface of the finished prepared hole.
Further, since the land does not hit the finished prepared hole, the finished hole can be finished with a cutting blade without any trouble, and the tool body can be smoothly extracted from the finished prepared hole. be able to.
[Brief description of the drawings]
FIG. 1 is a side view showing an embodiment of the present invention.
FIG. 2 is a front view of the same.
FIG. 3 is an enlarged view showing a front shape of the cutting blade.
FIG. 4 is an enlarged view showing a front shape of another example of the cutting blade.
FIG. 5 is a side view showing a conventional throw-away reamer.
FIG. 6 is an enlarged front view of the same.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tool body 2 Guide pad 3, 8 Throw away tip 4,6 Throw away reamer 5, 8a Cutting blade (cutting edge) 8b Escape surface 8c Scoop surface 8d Land 8e, 8f Arc surface (arc-shaped outer peripheral surface) 8g Arc-shaped outer peripheral surface C Tool Main body axis D Cutting blade rotation diameter D1 Guide pad arc surface rotation diameter E Land width H Pilot hole R1, R2 Turning radius T Tool body rotation direction

Claims (3)

In the throw-away reamer provided with a throw-away tip having a cutting edge projecting to the outer peripheral side of the tool body at the tip of the substantially cylindrical tool body rotated around the axis,
The flank facing the outer peripheral side of the tool body of the throw-away tip has a land having an arc-shaped outer peripheral surface formed such that the radius around the axis gradually decreases from the cutting edge toward the rear side in the cutting rotation direction. A throwaway reamer characterized in that is provided. 2. The throw away according to claim 1, wherein a width of the land in the cutting rotation direction is set within a range of 0.01 mm to half of a thickness of the throw away tip in the cutting rotation direction. Reamer. A guide pad that protrudes toward the outer periphery of the tool body and extends in the axial direction is provided on the outer periphery of the tool body, and the arc-shaped outer periphery of the land has a radius of curvature around the axis of the outer periphery of the guide pad. The throw-away reamer according to claim 1 or 2, wherein the throw-away reamer is set in a range between a turning radius and a turning radius 5 mm smaller than the turning radius.

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