JP4930313B2 - Reamer - Google Patents

Description

  The present invention relates to a reamer that performs a finishing process on a pilot hole that has been previously opened.

  Valve guide holes and the like are required to have high accuracy in terms of surface roughness, roundness, straightness, hole diameter, and the like. Therefore, high processing accuracy is required for the reamer used for finishing the valve guide hole and the like. As this type of reamer, there is a single-blade gun reamer described below. This gun reamer has a single cutting edge, and a margin portion is formed on the outer periphery of the cutting edge portion along the cutting edge, and is connected to the rear side in the tool rotation direction of the chip discharge groove. On the rear side in the tool rotation direction, a bearing portion is formed as a guide portion. Further, on the further rear side in the tool rotation direction of the bearing portion, the second portion extends along the ridge line on the rear side in the tool rotation direction of the chip discharge groove. A pad portion is formed as a guide portion.

In such a gun reamer, the inner periphery of the machining hole cut by the cutting blade is rubbed by the margin portion to obtain a smooth inner circumferential surface, and the bearing portion and the pad portion are in sliding contact with the inner circumferential surface of the machining hole. However, when the blade part moves forward, the blade part is guided so that the axis of the tool body coincides with the center axis of the machining hole. This prevents the blade from swinging and ensures straightness of the tool body. And high-precision drilling is performed. (For example, refer to Patent Document 1).
JP-A-8-066825 (second page, FIGS. 5 and 6)

  However, in the single-blade reamer including the single-blade gun reamer described above, when the so-called pilot hole is decentered in which the center of the pilot hole is deviated from the center of the reamer, the direction of the cutting resistance is kept substantially constant. However, since the magnitude of the cutting resistance fluctuates with the fluctuation of the cutting margin, there is a problem that the accuracy such as the hole diameter and roundness of the processed hole deteriorates. Further, in a single-blade reamer, since the cross-sectional shape becomes very unbalanced, elastic deformation such as bending and vibration increase due to the centrifugal force during rotation of the reamer, and the accuracy may be deteriorated. was there. Furthermore, the single-blade reamer has a problem in that it cannot be fed as compared with the multi-blade reamer and is not suitable for high-efficiency machining.

On the other hand, even in the multi-blade reamer, if the pilot hole is eccentric, the magnitude and direction of the resultant force of the cutting resistance will fluctuate greatly, and the accuracy of the hole diameter, roundness, and straightness of the processed hole will deteriorate. was there. Further, since the cutting resistance of each cutting edge becomes unbalanced due to the vibration between the cutting edges, there is a problem that the accuracy is deteriorated.
Even in a three-blade reamer having a relatively good cutting balance among multiple blade reamers, if the pilot hole is eccentric, the direction of the resultant force of the cutting resistance accompanying the rotation of the reamer varies greatly. It will get worse.

  The present invention has been made to solve the above-described problem, and provides a reamer that is superior in machining efficiency to a single-blade reamer without deteriorating the accuracy of the machining hole even when the pilot hole is eccentric. For the purpose.

In order to solve the above problems, the present invention has the following configuration.
According to the first aspect of the present invention, three grooves are formed at equal intervals in the circumferential direction of the tool main body at the tip of the substantially cylindrical tool main body rotated about the axis, and two of these grooves are Cutting edges are respectively formed on the tip ridges of the wall surfaces of the grooves facing the rotation direction, and a guide pad is formed on the outer peripheral surface of the cutting blade that is continuous with at least the cutting edge located on the rear side in the rotation direction. Reamer characterized by

  According to the first aspect of the present invention, since the three grooves are formed at equal intervals in the circumferential direction of the tool body at the tip of the tool body, the cross-sectional shape at each position of the tool body is balanced. In addition, since the elastic deformation and vibration of the tool body due to centrifugal force do not occur, the accuracy of the processing hole such as the hole diameter, roundness, and straightness of the processing hole does not deteriorate.

Furthermore, since cutting edges are respectively formed at the tip ridges of the wall surfaces facing the rotation direction of two grooves out of the three grooves, high-feed and high-efficiency machining can be performed as compared with a single-blade reamer.
The cutting force received by the reamer always acts in the same direction as the resultant force of the cutting forces received by the two cutting edges. At the same time, the guide pad provided on the outer peripheral surface connected to the cutting blade located on the rear side in the rotational direction of the two cutting blades makes the resultant force of the cutting resistance acting on the reamer by slidingly contacting the inner wall surface of the processing hole. Take it effectively. From the above, since elastic deformation such as bending of the reamer due to cutting resistance during machining is suppressed, the accuracy of the machining hole is improved.

According to a second aspect of the present invention, the guide pad is formed within a range of 127 ° to 173 ° on the rear side in the rotational direction with reference to a cutting blade located on the front side in the rotational direction among the cutting blades. The reamer according to claim 1.
According to the second aspect of the present invention, since the guide pad is formed within the above range, the resultant force of the cutting resistance received by the two cutting blades can be received more reliably. Elastic deformation is effectively suppressed. Therefore, the effect of improving the accuracy of the processed hole is particularly high. Furthermore, by limiting the formation range of the guide pad in the circumferential direction of the reamer to the above range, unnecessary sliding contact between the guide pad and the inner wall surface of the processing hole can be avoided. Therefore, an increase in load applied to the reamer due to the sliding contact is suppressed.
When the formation range of the guide pad deviates from the above range, the resultant force of cutting resistance cannot be reliably received by the guide pad, so that there is a possibility that the effect of improving the accuracy of the machining hole cannot be obtained sufficiently.
In order to further enhance the effect of improving the accuracy of the machining hole, the guide pad has an entire range of 127 ° to 173 ° on the rear side in the rotational direction with reference to the cutting blade located on the front side in the rotational direction among the cutting blades. It is desirable to be formed over.

The invention according to claim 3 is the reamer according to claim 1 or 2, wherein the cutting blade is made of an ultra-high pressure sintered body.
According to the invention of claim 3, when the cutting blade is made of an ultra-high pressure sintered body, it becomes possible to cut non-ferrous metals such as aluminum and aluminum alloy at high speed. It is possible to prevent deterioration of the surface roughness of the inner surface of the processed hole due to the adhesion of the material. Furthermore, the high wear resistance prolongs the cutting edge life and prevents the surface roughness from deteriorating over a long period of time. And since the balance of the cross-sectional shape in each position of a tool main body is excellent, the deterioration of the precision of the processing hole resulting from the elastic deformation and vibration by a centrifugal force is prevented.

The invention according to claim 4 is characterized in that an oil hole is provided in the interior of the reamer, and the oil hole opens on the wall surface of the groove. Reamer.
According to the invention which concerns on Claim 4, since fluids, such as the cutting oil discharged from the said oil hole, and high pressure air, are reliably supplied to a cutting blade, the cooling of a cutting blade during cutting, a cutting blade, and a workpiece And can be lubricated. Therefore, adhesion of the work material to the cutting edge and damage to the cutting edge are reduced, and the surface roughness of the inner surface of the machining hole and the cutting edge life of the reamer are improved.

According to the present invention, since three grooves are formed at equal intervals in the circumferential direction of the tool body at the tip of the tool body, the cross-sectional shape at each position of the tool body is unbalanced. This prevents the reamer from being elastically deformed or vibrated by centrifugal force, so that the machining accuracy of the machined hole is improved.
Furthermore, since cutting edges are respectively formed at the tip ridges of the wall surfaces facing the rotation direction of two grooves out of the three grooves, high-feed and high-efficiency machining can be performed as compared with a single-blade reamer.
The cutting force received by the reamer always acts in the same direction as the resultant force of the cutting forces received by the two cutting edges. At the same time, the guide pad provided on the outer peripheral surface connected to the cutting blade located on the rear side in the rotational direction of the two cutting blades makes the resultant force of the cutting resistance acting on the reamer by slidingly contacting the inner wall surface of the processing hole. Take it effectively. From the above, since elastic deformation such as bending of the reamer due to cutting resistance during machining is suppressed, accuracy such as machining hole position, hole diameter, roundness, and straightness is improved.
From the above, it is possible to provide a reamer excellent in processing efficiency and processing hole accuracy.

  Embodiments to which the present invention is applied will be described with reference to the drawings. FIG. 1 is a front view of a reamer to which the present invention is applied. 2 is an enlarged side view of the reamer shown in FIG.

  As shown in FIGS. 1 and 2, this reamer includes a blade portion 2 formed on the distal end side of a round bar-shaped tool body 1 that is rotated around an axis, and a shank portion 3 formed on the proximal end side. Become. On the outer peripheral surface of the blade portion 1, three grooves 4 are extended from the distal end surface of the blade portion 2 toward the proximal end side at substantially equal intervals in the circumferential direction of the reamer. As can be seen from the side view in the front end view of FIG. 2, these three grooves 4 are formed to have substantially the same cross-sectional shape and substantially the same length in the axial direction. Two of these three grooves 4 are formed with cutting edges 5A and 5B at the ridges of the wall surfaces facing the rotation direction K of the reamer, respectively, and the remaining one groove 4 faces the rotation direction. A dummy cutting edge 5C that is slightly retracted to the base end side with respect to the cutting edges 5A and 5B is formed at the leading edge of the wall surface so as not to contact the work material during cutting.

  As shown in FIG. 2, a guide pad 7 is formed on the outer peripheral surface of the two cutting blades 5A and 5B that is continuous with the cutting blade 5B (second cutting blade) located on the rear side in the rotation direction K. The guide pad 7 extends from the ridge line intersecting the distal end surface of the blade portion 2 in the reamer axial direction to the vicinity of the end portion of the groove 4 and is connected to the cutting blade 5B (second cutting blade) in the circumferential direction. Is formed over. And the cross-sectional shape in each position of the surrounding surface of the guide pad 7 is substantially circular arc shape, and it corresponds to the circle which the outermost diameter end of the cutting blades 5A and 5B draws, or it is retracted just inside the said circle. Formed. Further, the diameter of the arc of the cross-sectional shape is equal to or slightly smaller than the diameter of the circle drawn by the outermost peripheral ends of the cutting edges 5A and 5B.

  Among the two cutting edges, a margin 6 having a predetermined width is formed from the cutting edge 5A located on the front side in the rotation direction K and the dummy cutting edge 5C toward the rear side in the rotation direction K. Further, a guide pad 7 having a small width in the rotation direction K is formed on the intersection ridge line portion between the outer peripheral surface of the margin 6 in the rotation direction K rear side and the groove 4. The cross-sectional shape at each position of the peripheral surface of the margin 6 and the narrow guide pad 7 is substantially arc-shaped, and coincides with the circle drawn by the outermost diameter ends of the cutting edges 5A and 5B, or is slightly inside the circle. It is formed to retract. Further, the diameter of the arc of the cross-sectional shape is equal to or slightly smaller than the diameter of the circle drawn by the outermost peripheral ends of the cutting edges 5A and 5B.

  This type of reamer is used for spreading a prepared hole formed by drilling, forging, casting, or the like to finish a predetermined hole diameter. In general, when the so-called pilot hole is eccentric, the center of the reamer is not coincident with the center of the pilot hole, the multi-blade reamer provided with a plurality of cutting edges in the circumferential direction faces the diameter direction across the axis. The cutting force is unbalanced due to fluctuations in the cutting margin between the cutting edges, and the magnitude and direction of the resultant force of the cutting resistance greatly vary with the rotation of the reamer. Therefore, elastic deformation such as bending of the tool body is increased, and the accuracy of the machining hole such as the machining hole position, the hole diameter, the roundness and the straightness is deteriorated. Even in the single-blade reamer, when the pilot hole is eccentric, the direction of the cutting force is kept substantially constant, but the magnitude of the cutting force varies with the variation of the cutting margin. There was a problem that accuracy such as hole diameter and roundness deteriorated. In addition, since the cross-sectional shape of a single-blade reamer is very unbalanced, elastic deformation such as bending and vibration increase due to the centrifugal force during rotation of the reamer. Accuracy such as circularity will deteriorate. Furthermore, the single-blade reamer has a problem in that it cannot be fed as compared with the multi-blade reamer and is not suitable for high-efficiency machining.

  In the reamer to which the present invention is applied, three blades 4 having substantially the same cross-sectional shape are formed in the blade portion 2 at substantially equal intervals in the circumferential direction and substantially the same length in the axial direction. The cross-sectional shape at each position of the tool body 1 is excellent in balance, and the tool body is not elastically deformed or vibrated by centrifugal force. Therefore, the accuracy of the hole diameter and roundness of the processed hole is improved compared to the single-blade reamer. To do.

  Furthermore, in the reamer to which the present invention is applied, when the pilot hole is eccentric, the pair of cutting blades do not face each other in the diameter direction across the axis of the reamer. . Therefore, the unbalance of the cutting resistance of each cutting edge is improved, and elastic deformation such as bending during cutting does not occur. Therefore, compared to the conventional multi-blade reamer, the processing hole position, hole diameter, roundness and straightness The hole accuracy does not deteriorate.

  Furthermore, the resultant force of the cutting resistance received by the reamer always acts in the same direction as the resultant force of the cutting resistance received by the two cutting edges 5A and 5B, and is positioned on the rear side in the rotational direction of the two cutting edges 5A and 5B. A guide pad 7 is provided on the outer peripheral surface continuous with the cutting blade 5B (second cutting blade) to be received, and a part or the whole of the guide pad 7 receives a cutting resistance received by the reamer by being in sliding contact with the inner wall surface of the machining hole. Therefore, the enlargement and bending of the processed hole are suppressed, the accuracy of the processed hole is improved, and an increase in cutting resistance due to the sliding contact is prevented.

  Since two of the three grooves 4 are formed with cutting edges 5A and 5B at the ridges of the wall surface facing the rotation direction K of the reamer, respectively, it is possible to feed higher than a single-blade reamer, so high efficiency Processing becomes possible.

  The guide pad 7 in this reamer does not need to be formed over the entire outer peripheral surface that continues from the cutting edge 5B (second cutting edge) located on the rear side in the rotational direction K, but on the cutting edge 5A located on the front side in the rotational direction K ( What is necessary is just to be formed in 127 to 173 degrees in the rotation direction K back side on the basis of a 1st cutting edge. If the guide pad 7 is formed at least within the above range, elastic deformation such as bending of the reamer can be effectively suppressed by reliably receiving the resultant force of the cutting resistance received by the two cutting blades 5A and 5B. Therefore, in addition to improving the machining hole accuracy such as the machining hole position, the hole diameter, the roundness and the straightness, the load due to the sliding contact between the guide pad 7 and the inner wall surface of the machining hole is reduced. When the formation range of the guide pad 7 deviates from the above range, the resultant force of the cutting resistance cannot be reliably received by the guide pad, and thus the above effect may not be sufficiently obtained. In order to increase the above effect, the guide pad 7 is formed over the entire range of 127 ° to 173 ° on the rear side in the rotation direction K with reference to the cutting edge 5A located on the front side in the rotation direction K. desirable.

  In this reamer, the cutting edges 5A and 5B may be formed of a diamond sintered body or an ultrahigh pressure sintered body such as cBN. If the cutting edges 5A and 5B are made of a diamond sintered body in this way, high-speed machining of non-ferrous metals such as aluminum and aluminum alloys becomes possible and the work material is agglomerated as compared with the case of making a general cemented carbide. The wearing is suppressed and the life of the cutting blade is extended. In addition, when the cutting blade is made of cBN, the cast iron can be processed at a high speed and the cutting blades 5A and 5B can have a longer life compared to a general cemented carbide. When the cutting blades 5A and 5B are made of an ultra-high pressure sintered body in this way, the number of revolutions of the reamer becomes very high as the speed increases, so elastic deformation and vibration such as bending of the reamer due to centrifugal force. However, since each reamer has a well-balanced cross-sectional shape as described above, it is possible to suppress bending and run-out during rotation. Therefore, high accuracy of the machining hole in high-speed machining is realized.

  In this reamer, it is desirable that an oil hole 8 is provided inside the tool body 1 and that the oil hole 8 is opened in the wall surface of the groove 4. The oil holes 8 opened in the wall surfaces of the grooves 4 are preferably directed to the corresponding cutting edges 5A and 5B, respectively. When the oil hole 8 is provided in this way, fluid such as cutting oil and high-pressure air discharged from the oil hole 8 is reliably supplied to the cutting blades 5A and 5B, so that the fluid is supplied from the outside of the reamer. Compared with what is supplied, cooling of the cutting edges 5A and 5B during cutting and lubrication of the cutting edges 5A and 5B and the work material are performed effectively. Therefore, damage to the cutting blades 5A and 5B is reduced, and the life of the reamer is extended.

  The results of a comparison between the reamer of this embodiment and the conventional reamer will be described below with respect to the direction and magnitude of the cutting resistance when the reamer and the pilot hole are displaced from each other in the center position.

  3D, the center of the pilot hole is shifted to the X axis direction positive side in the XY coordinates with the center of the reamer as the origin O. A machining situation was assumed in which the maximum cutting margin apmax in the radial direction was twice the minimum cutting margin apmin at the position B. The amount by which the first cutting edge initially at position A moves in the rotational direction by the rotation of the reamer is represented by phase θ. The table of FIG. 3 (a) shows the phase of the first cutting edge initially at position A for each of the conventional single-blade reamer, 2-blade reamer, 3-blade reamer and reamer to which the present invention is applied. When θ is divided into 30 ° increments in the range of 0 ° to 360 ° (one rotation), the magnitude of the cutting resistance of each cutting edge in each phase θ, and the direction and magnitude of the resultant force of the cutting resistance are shown. . In the table, the number of cutting blades is different, but this is due to the difference in the number of blades of each reamer. The direction of the resultant force of the cutting resistance is 0 ° in the direction parallel to the normal line on the outer peripheral side of the first cutting edge and facing outward, and the direction in the direction parallel to the tangential line on the outer peripheral side of the first cutting edge and facing backward in the rotational direction K. 90 °. The magnitude of the resultant force of the cutting resistance is expressed as a ratio when the magnitude of the resultant force of the cutting resistance acting at the moment when the cutting edge (first cutting edge) initially at position A cuts the maximum cutting margin apmax is 100. . (B) and (c) of FIG. 3 are graphs of the table of (a), (b) is a graph showing the relationship between each phase θ and the direction of the resultant force of the cutting resistance, (c ) Is a graph showing the relationship between each phase θ and the magnitude of the resultant force of the cutting force.

  As can be seen from FIGS. 3B and 3C, in the single-blade reamer, the direction of the resultant force of the cutting force is always 90 °, but the magnitude of the resultant force of the cutting force is directly affected by fluctuations in the cutting margin. Greatly affecting the range of 50-100. In the two-blade reamer, the cutting force of each cutting edge becomes unbalanced due to the influence of the cutting margin in the radial direction, so that the direction of the resultant force of the cutting force varies by approximately 360 °, and the magnitude of the resultant force of the cutting force is 0 to 0. It fluctuates greatly in the 100 range. In a general three-blade reamer in which three cutting blades are arranged at substantially equal intervals in the circumferential direction, the magnitude of the resultant force of the cutting force is small, but the direction of the resultant force of the cutting force is 30 ° to 270 °. It fluctuates greatly in the range.

  In the reamer to which the present invention is applied, the distance between two cutting edges is narrow in the circumferential direction. Significantly smaller than reamer. Specifically, the direction of the resultant force of the cutting force is in the range of 127 ° to 173 °, and the fluctuation width is smaller than that of the conventional two-blade reamer and three-blade reamer. The first cutting edge is directed to the outer peripheral surface side continuous with the second cutting edge located on the rear side in the rotation direction. Furthermore, the magnitude of the resultant force of the cutting force is in the range of 67 to 88, and the fluctuation width is smaller than that of the conventional single-blade reamer and double-blade reamer.

  As described above, in the reamer to which the present invention is applied, even if the magnitude of the cutting resistance of each cutting edge becomes unbalanced, the resultant force of the cutting resistance is based on the center of the reamer. Since it is directed to the outer peripheral surface side connected to the second cutting edge 5B located on the rear side in the rotational direction of 5A, it is possible to effectively suppress the bending due to the cutting resistance of the reamer by providing the guide pad 7 on the outer peripheral surface. it can. Furthermore, the variation in the magnitude of the resultant force of the cutting force is also significantly smaller than the conventional single-blade reamer and double-blade reamer. This is also a factor that significantly suppresses the bending by the guide pad 7.

It is a front view of the reamer to which the present invention is applied. FIG. 2 is an enlarged side view of the reamer shown in FIG. It is a figure explaining the direction and magnitude | size of the resultant force of cutting resistance at the time of processing the prepared hole where the center shifted | deviated, (a) is each phase (theta) of a 1st cutting edge about the reamer to which the conventional reamer this invention is applied. Is a table showing the magnitude of the cutting force of the cutting edge, the direction and magnitude of the resultant force of the cutting force, and (b) is a graph showing the relationship between each phase θ and the direction of the resultant force of the cutting resistance, c) is a graph showing the relationship between each phase θ and the magnitude of the resultant force of the cutting force, and (d) is a schematic diagram of the machining situation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tool body 2 Blade part 3 Shank part 4 Groove 5A Cutting blade (1st cutting blade)
5B cutting edge (second cutting edge)
5C Dummy cutting edge 6 Margin 7 Guide pad 8 Oil hole

Claims (3)

Three grooves are formed at equal intervals in the circumferential direction of the tool body at the front end portion of the substantially cylindrical tool body that is rotated around the axis, and two grooves out of these grooves face the rotation direction. A first cutting edge and a second cutting edge located behind the first cutting edge in the rotation direction of the tool body are formed on the tip ridge of the wall surface, and the wall surface of the remaining one groove facing the rotation direction is formed. A dummy cutting edge that is not involved in cutting is formed on the tip edge,
On the outer peripheral surface of the tool body adjacent to the first cutting edge, a first margin and a first margin formed adjacent to the first margin and retreating toward the center side of the tool body from the first margin. A recess portion and a first guide pad formed adjacent to the recess portion and projecting in the circumferential direction of the tool body from the recess portion to the same extent as the first margin are formed.
A second guide pad is formed on the entire outer peripheral surface of the tool body adjacent to the second cutting edge,
On the outer peripheral surface of the tool body adjacent to the dummy cutting edge, a second margin and a second recess formed adjacent to the second margin and receding toward the center of the tool body from the second margin. And a third guide pad formed adjacent to the recess and projecting in the circumferential direction of the tool body from the recess to the same extent as the second margin. The reamer according to claim 1, wherein the cutting blade is made of an ultra-high pressure sintered body. The reamer according to claim 1 or 2, wherein an oil hole is provided in the inside, and the oil hole opens in a wall surface of the groove.

Images