JP2009119542A - Rotating tool for drilling and manufacturing method of yoke for universal-joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotating tool for drilling capable of forming a hole with high drilling accuracy in a drilling object. <P>SOLUTION: A rotating tool 1 for drilling is formed in a stepped shape, having a blade part for reamer drilling, a blade part for burnishing drilling, and a shank part sequentially from a tip side, with a diameter of the blade part for reamer drilling made smaller than the blade part for burnishing drilling. The blade part for reamer drilling includes a cutting edge 13, and the blade part for burnishing drilling includes a round land 21, a front flank relief 22 connected to an end portion of the round land 21 in a forward direction of a rotation of a tool, and a back flank relief 23 connected to the end portion of the round land 21 in a backward direction of the rotation of the tool. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rotary tool for drilling holes for finishing a hole formed in a workpiece with a predetermined machining accuracy, and a method for manufacturing a universal joint yoke using the rotary tool for drilling holes.

  For example, universal joint yokes 101 and 103 that constitute a universal joint 100 as shown in FIG. 6 may be cited as workpieces that require high machining accuracy for machined holes. In addition to these yokes 101 and 103, the universal joint 100 includes a cross shaft 110 and a bearing 111, and connects shafts 112 and 113 whose axes intersect at a certain angle. The rotational force of one shaft 112 is applied to the other shaft 113. For example, it is provided in an automobile steering device or the like.

  The universal joint yokes 101 and 103 are provided with a pair of facing portions 102 and 104 facing each other at a predetermined interval. The facing portions 102 and 104 have mounting holes (through holes) 102a to which the bearing 111 is attached. 105 is formed coaxially and parallel to the facing direction of the facing portions 102 and 104. The one shaft 112 is connected to the yoke 101, and the other shaft 113 is connected to the yoke 103. Note that a notch 104 a provided so as to cover the mounting hole 105 is formed on the facing surface of the facing portion 104 of the yoke 103.

  The cross shaft 110 is configured such that the axes are orthogonal to each other, and the bearing 111 rotatably supports both ends of the shaft constituting the cross shaft 110.

  The mounting holes 102a and 105 of the universal joint yokes 101 and 103 are required to have high machining accuracy. Conventionally, for example, as a tool for machining such a hole that requires high machining accuracy, for example, a special A burnishing drill as disclosed in Kaihei 6-39617 has been proposed (see FIGS. 7 and 8).

  As shown in FIGS. 7 and 8, the burnishing drill 200 is formed so as to extend along the axial direction of the drill 200 and to be connected to the shank portion 201. In addition, the first land 202, the second land 203, and the third land 204 formed at positions having different phases, grooves 205, 206, and 207 formed between the lands 202, 203, and 204, and the drill 200 A drill blade 208, a reamer blade 209, and a reamer surface 210 are formed at positions where the phase is different on the tip side.

  The first land 202, the second land 203, and the third land 204 are formed such that the tip end side in the axial direction of the drill 200 has a small diameter, and the diameters of the second land 203, the third land 204, and the first land 202 are further reduced. Smaller diameter in order.

  The drill blade 208 is connected to the outer peripheral surface of the first land 202, and the reamer blade 209 is connected to the outer peripheral surface of the third land 204. The reamer surface 210 is formed in a planar shape so that the end portion in the rotation reverse direction is positioned on the outer side in the radial direction of the drill 200 than the end portion in the rotation forward direction of the drill 200, and the second land 203. It is formed so as to be connected to the outer peripheral surface. Further, the positional relationship among the drill blade 208, the reamer blade 209, and the reamer surface 210 is such that the drill blade 208 is positioned closer to the tip of the drill 200 than the reamer blade 209, and the reamer blade 209 is closer to the tip of the drill 200 than the reamer surface 210. Is located.

  In the burnishing drill 200 configured as described above, when the drill 200 is moved to the workpiece while rotating about the axis, a pilot hole is formed by the drill blade 208, and the pilot hole formed by the drill blade 208 is formed. A hole processed by the reamer blade 209 and processed and formed by the reamer blade 209 is polished by the reamer surface 210, whereby a predetermined hole is formed in the workpiece.

JP-A-6-39617

  However, in the conventional burnishing drill 200 described above, the intersection of the reamer surface 210 with the end of the rotation direction of the drill 200 and the surface 205a constituting the groove 205 is a corner, and this corner is cut off. Since the inner surface of the hole is cut by using a blade, there is a certain limit to obtaining high-precision machining accuracy. In addition, the corner portion of the second land 203 has a cutting edge in the same manner as described above, because the intersection between the end portion of the rotation direction of the drill 200 and the surface 205a constituting the groove 205 is a corner. As a result, the inner surface of the hole is cut and processing accuracy exceeding a certain level cannot be obtained.

  The present invention has been made in view of the above circumstances, and is a rotary tool for drilling capable of forming a hole with higher processing accuracy in a workpiece, and a universal joint using the rotary tool for drilling It is an object of the present invention to provide a manufacturing method for an industrial yoke.

To achieve the above object, the present invention provides:
A rotary tool for drilling in which a blade part for reaming, a blade part for burnishing, and a shank part are formed sequentially from the tip side,
The diameter of the reaming blade is smaller than the burnishing blade, and is formed into a stepped shape.
The blade portion for reaming includes a cutting edge,
The burnishing blade has a round land, a front flank connected to the end of the round land in the tool rotation forward direction, and a rear flank connected to the end of the round land in the tool rotation reverse direction. It is related with the rotary tool for drilling characterized by comprising.

  According to this drilling rotary tool, for example, it can be drilled as described below. First, after attaching a drilling rotary tool and a workpiece on which a pilot hole has been formed in advance to a machine tool, the drilling rotary tool is rotated about its axis, and predetermined along the axial direction of the drilling rotary tool. Is moved in a direction approaching the workpiece at a feed rate of.

  Then, first, the reaming blade portion is inserted into the prepared hole of the workpiece, and the prepared hole is reamed by the reaming blade portion (cutting edge). Thereafter, the burnishing blade portion is inserted into the hole formed and formed by the reaming blade portion, and the hole is burnished by the burnishing blade portion.

  In this burnishing process, since the diameter of the burnishing blade is larger than that of the reaming blade, the burnishing blade (front flank) rotates while crushing the convex portion on the inner surface of the hole. At this time, the surface layer of the inner surface of the hole is plastically deformed by the blade portion for burnishing processing, whereby the convex portion of the inner surface of the hole is crushed and the concave portion of the inner surface of the hole is filled, Since the inner surface of the hole is smoothed and further smoothed by the round land, the roundness of the hole is improved. At the same time, a compressive residual compressive force is applied by plastic deformation of the surface layer on the inner surface of the hole, and the surface modification of the inner surface of the hole is performed. For example, mechanical properties such as fatigue strength, wear resistance, and hardness are enhanced.

  In this way, when reaming and burnishing are sequentially performed, the hole drilling rotary tool is moved along the axial direction in a direction away from the workpiece at a predetermined speed. Thereby, a series of drilling steps for the workpiece using the rotary tool for drilling is completed.

  By the way, in the rotary tool for hole machining according to the present invention, the front flank connected to the end portion of the round land in the tool rotation forward direction is formed on the blade portion for burnishing. This is because the corner of the round land end in the tool rotation forward direction is dropped and this corner becomes a cutting edge to prevent the inner surface of the hole from being cut.

  Therefore, according to the rotary tool for hole machining according to the present invention, it is possible to prevent the cutting process from being performed by the blade part for burnishing, and therefore the blade part for reaming by the blade part for burnishing. The holes formed and processed with can be finished with higher accuracy.

  In addition, it is preferable that the clearance angle of the front flank is set within a range of 10 ° to 40 °. This is because when the clearance angle is smaller than 10 °, the end portion (corner portion) opposite to the round land connection side of the front clearance surface acts as a cutting edge to cut the inner surface of the hole. It is. Also. This is because the cutting performed in this way has a large cutting resistance and is liable to cause chatter vibration of the tool, so that the processing accuracy is reduced. On the other hand, when the clearance angle is larger than 40 °, the front clearance surface rises with respect to the inner surface of the hole, so that the resistance during burnishing increases and the chatter vibration of the tool easily occurs. This is because accuracy decreases.

  More preferably, the clearance angle of the front flank is within a range of 20 ° to 30 °. This is because the inconvenience as described above can be more effectively prevented and a more remarkable effect can be obtained within this angle range.

  The rear flank preferably has a flank angle in the range of 30 ° to 60 °. This is because if the clearance angle is smaller than 30 °, the rear clearance surface may come into contact with the inner surface of the hole. If the clearance angle is larger than 60 °, the burnishing blade becomes thin. This is because there arises a problem that the strength is lowered.

  Moreover, it is preferable that the width | variety of the said round land is set in the range of 1 mm-3 mm. This is because when the width of the round land is smaller than 1 mm, the strength is weakened, and the portion where the round land and the inner surface of the hole are in contact with each other decreases, so that the surface layer of the inner surface of the hole is plastically deformed. This is because it becomes difficult and as a result, the processing accuracy is lowered. If the width of the round land is larger than 3 mm, the portion where the round land and the inner surface of the hole are in contact with each other increases. This is because the resistance at the time increases, causing seizure and chatter vibration of the tool, and the machining accuracy decreases.

  Moreover, it is preferable that the diameter difference between the blade portion for reaming and the blade portion for burnishing is set within a range of 10 μm to 20 μm. This is because if the difference in diameter is smaller than 10 μm, the convex portion of the inner surface of the hole cannot be crushed so much, and the surface of the hole is still uneven even after burnishing, and good processing accuracy is obtained. Because you can't. On the other hand, when the difference in diameter is larger than 20 μm, the portion of the blade portion for burnishing that comes into contact with the convex portion of the inner surface of the hole becomes large, the resistance during burnishing increases, and tool chatter vibration is likely to occur. Or the convex part of the inner surface of the hole is peeled off and high machining accuracy cannot be obtained, or when the tool moves in the hole from one opening of the hole to the opening on the opposite side, burnishing The convex portion on the inner surface of the hole is pushed toward the opening on the opposite side by the blade portion and pushed out from the opening, and burrs are generated at the edge of the opening, thereby increasing the deburring process. This is because the problem arises.

  Moreover, it is preferable that at least the burnishing blade portion of the rotary tool for drilling is coated with TiN (titanium nitride), and in this way, welding resistance, heat resistance and wear resistance are provided. Etc. can be improved.

The present invention also provides:
A method of manufacturing a universal joint yoke having a pair of facing portions facing each other at a constant interval, the pair of facing portions having a through-hole parallel to the facing direction formed coaxially,
First, a pilot hole is formed in each of the facing portions corresponding to the formation position of the through hole,
Next, the drilling rotary tool according to any one of claims 1 to 6 and the universal joint yoke are arranged such that the axis of the drilling rotary tool and the axis of the through hole to be formed are coaxial. And arranged so as to be spaced from one of the opposing portions,
While rotating the drilling rotary tool about the axis, the one facing part along the axis of the drilling rotary tool until the burnishing blade passes through the lower hole of the other facing part And moving the blade portion for reaming and the blade portion for burnishing processing sequentially through the prepared holes of the one facing portion and the other facing portion,
According to a method for manufacturing a universal joint yoke, wherein the hole drilling rotary tool is removed by moving the hole drilling rotary tool along the axis thereof in a direction away from the universal joint yoke. .

  According to this method for manufacturing a universal joint yoke, since the hole drilling rotary tool enables processing with higher processing accuracy, a highly accurate through hole is formed by a pair of opposing portions of the universal joint yoke. be able to.

  As described above, according to the rotary tool for drilling according to the present invention, a hole with high machining accuracy can be formed by the workpiece. Moreover, according to the method for manufacturing a universal joint yoke according to the present invention, it is possible to manufacture a universal joint yoke including a pair of opposed portions in which through holes with high processing accuracy are formed.

  Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings. 1 is a front view showing a schematic configuration of a rotary tool for drilling according to an embodiment of the present invention, FIG. 2 is a bottom view in the direction of arrow A in FIG. 1, and FIG. FIG. 3 is a detailed view of a portion B in FIG. 2. Moreover, FIG. 4 is explanatory drawing for demonstrating the manufacturing method of the universal joint yoke based on this embodiment.

  First, the drilling rotary tool will be described. As shown in FIG. 1 to FIG. 3, the rotary tool 1 for hole drilling of this example includes a blade part 10 for reaming, a blade part 20 for burnishing, and a shank part 30 that are sequentially formed from the tip side. The diameter of the reaming blade 10 is smaller than the burnishing blade 20, and the diameter of the burnishing blade 20 is smaller than the shank 30. The blade portion 10 for reaming and the blade portion 20 for burnishing are formed in a straight blade shape formed continuously toward the shank portion 30 side. Further, the hole machining rotary tool 1 includes a TiN (titanium nitride) coating on the entire surface including the blade portion 10 for reaming and the blade portion 20 for burnishing.

  The reaming blade portion 10 includes a cutting edge 13 constituted by a rake face 11 and a flank face 12 (including a margin part having no relief angle and a part having a relief angle), a cutting edge 13 and A land 14 including the flank 12 and a blade groove 15 formed between the lands 14 are provided. A plurality of the cutting blade 13, the land 14 and the blade groove 15 are provided in the same shape at different positions. ing. A chamfered portion 16 is formed at the tip of the blade portion 10 for reaming.

  The burnishing blade portion 20 is formed by extending the land 14 and the blade groove 15 of the reaming blade portion 10 toward the shank portion 30 and is in sliding contact with the inner surface of the hole of the workpiece. A round land 21 is provided. A front flank 22 is connected to the end of the round land 21 in the rotation forward direction of the tool 1, and the end of the round land 21 in the reverse rotation direction of the tool 1 is on the rotation forward side of the blade groove 15. The side flank 15a is extended and connected, and the rear flank 23 of the round land 21 is formed by the side flank 15a. The round lands 21, the front flank 22 and the rear flank 23 are provided in a plurality with the same shape at different phases.

  The clearance angle α of the front flank 22 is set within a range of 10 ° to 40 ° (more preferably 20 ° to 30 °), and is perpendicular to the radial direction of the round land 21 of the side surface 15a and round. An inclination angle (a clearance angle of the rear flank 23) β with respect to the surface in contact with the land 21 is set within a range of 30 ° to 60 °, and a width γ of the round land 21 is set within a range of 1 mm to 3 mm. The The diameter difference δ between the reaming blade 10 and the burnishing blade 20 is set within a range of 10 μm to 20 μm.

  Next, a method for manufacturing a universal joint yoke using the hole drilling rotary tool 1 will be described. In the following description, the universal joint yoke 103 shown in FIG. 6 will be described as an example, but the universal joint yoke 103 is not limited to this.

  First, pilot holes 105a are formed in portions of the facing portions 104 corresponding to the positions where the mounting holes 105 are formed, and then the universal joint yoke 103 and the hole machining rotary tool 1 are connected to the axis of the hole machining rotary tool 1. Are attached to the machine tool so that the axis of the attachment hole 105 to be formed is coaxial and spaced from one of the opposing portions 104 (see FIG. 4A). 1 is rotated about the axis, and moved in the direction of approaching the universal joint yoke 103 at a predetermined feed speed along the axial direction of the drilling rotary tool 1.

  When the reaming blade portion 10 is inserted into the prepared hole 105a of the one opposing portion 104, the reaming blade portion 10 (cutting blade 13) reams the prepared hole 105a (see FIG. 4 (b)). The reamed pilot hole 105a is denoted by reference numeral 105b.

  Next, the burnishing blade portion 20 is inserted into the hole 105b formed and formed by the reaming blade portion 10, and the hole 105b is burnished by the burnishing blade portion 20. The reaming blade portion 10 is inserted into the prepared hole 105a of the other facing portion 104, and the prepared hole 105a is reamed (see FIG. 4C).

  Thereafter, the burnishing blade 20 is inserted into the hole 105b formed and formed by the reaming blade 10, and the hole 105b is burnished (see FIG. 4D).

  In the burnishing, the diameter of the burnishing blade 20 is larger than that of the reaming blade 10, so that the burnishing blade 20 (front flank 22) is convex on the inner surface of the hole 105b. However, at this time, the surface layer of the inner surface of the hole 105b is plastically deformed by the burnishing blade 20 so that the convex portion of the inner surface of the hole 105b is crushed. Then, the concave portion on the inner surface of the hole 105b is filled, the inner surface of the hole 105b is smoothed, and further smoothed by the round land 21, so that the roundness of the hole 105b (mounting hole 105) is increased. improves. At the same time, a compressive residual compressive force is applied by plastic deformation of the surface layer on the inner surface of the hole 105b, and the surface modification of the inner surface of the hole 105b (mounting hole 105) is performed. For example, fatigue strength, wear resistance, hardness The mechanical properties such as are enhanced.

  In this way, while rotating the drilling rotary tool 1 about the axis, the drilling rotary tool 1 is moved until the burnishing blade 20 penetrates the pilot hole 105a of the other facing portion 104. Then, the blade portion 10 for reaming and the blade portion 20 for burnishing are sequentially passed through the prepared hole 105a of one facing portion 104 and the other facing portion 104 (reaming is performed in the prepared hole 105a of each facing portion 104). When the drilling rotary tool 1 is moved in the direction away from the universal joint yoke 103 at a predetermined speed along the axial direction, the hole drilling rotary tool 1 is removed from the mounting holes 105 of the opposing portions 104. Thus, a series of steps for manufacturing the universal joint yoke 103 by forming the attachment holes 105 in the respective facing portions 104 using the hole machining rotary tool 1 is completed.

  By the way, in the rotary tool 1 for drilling of the present example, as described above, the front flank 22 having the clearance angle α set in the range of 10 ° to 40 °, the clearance on the blade portion 20 for burnishing. The rear flank 23 having the angle β set in the range of 30 ° to 60 ° is formed, and the width γ of the round land 21 is set in the range of 1 mm to 3 mm.

  The front flank 22 is formed, that is, the corner of the end of the round land 21 in the tool rotation forward direction is dropped. This corner becomes a cutting edge and the inner surface of the hole 105b is cut. This is to prevent it.

  Also, the clearance angle α of the front flank 22 is set within the range of 10 ° to 40 ° when the clearance angle α is smaller than 10 ° and the round lands 21 side of the front flank 22 This is because the opposite end (corner) 22a acts as a cutting edge and the inner surface of the hole 105b is cut. Further, the cutting performed in this way has a large cutting resistance, and chatter vibration of the tool 1 is likely to occur, so that the processing accuracy is lowered. On the other hand, when the clearance angle α is larger than 40 °, the front clearance surface 22 rises with respect to the inner surface of the hole 105b, so that the resistance during burnishing increases and chatter vibration of the tool 1 occurs. This is because the processing accuracy is reduced.

  The clearance angle α of the front flank 22 is more preferably in the range of 20 ° to 30 ° from the viewpoint of more effectively preventing such inconvenience.

  In addition, the clearance angle β of the rear flank 23 is set within the range of 30 ° to 60 ° when the clearance angle β is smaller than 30 ° and the rear flank 23 contacts the inner surface of the hole 105b. Because there is a risk of doing. Further, when the rear flank 23 is formed by the side surface 15a of the blade groove 15 as in this example, the blade groove 15 becomes small, so that the chips do not easily escape and easily accumulate in the blade groove 15. This is because the chips may be caught between the round land 21 or the front flank 22 and the inner surface of the hole 105b. On the other hand, when the clearance angle β is larger than 60 °, there is a problem that the blade portion 20 for burnishing is thinned and the strength is lowered.

  In addition, the width γ of the round land 21 is set within a range of 1 mm to 3 mm because the strength becomes weak when the width γ of the round land 21 is smaller than 1 mm, This is because the portion in contact with the inner surface of the hole 105b is reduced, which makes it difficult to plastically deform the surface layer on the inner surface of the hole 105b, resulting in a problem that processing accuracy is lowered. On the other hand, when the width γ of the round land 21 is larger than 3 mm, the portion where the round land 21 and the inner surface of the hole 105b are in contact with each other increases, so that resistance during burnishing increases and seizure or chatter of the tool 1 occurs. This is because vibration is caused and machining accuracy is lowered.

  Therefore, if the blade part 20 for burnishing is configured as described above, it is possible to effectively prevent the above-described problems from occurring. For example, the cutting part 20 is burned by the burnishing blade 20. This prevents the front flank 22 from sleeping or rising from the inner surface of the hole 105b, and suppresses resistance during burnishing and prevents chatter vibration of the tool 1 from occurring. can do. Thereby, the hole 105b processed and formed by the blade part 10 for reaming can be finished with higher accuracy by the blade part 20 for burnishing.

  Moreover, since the diameter difference δ between the blade portion 10 for reaming and the blade portion 20 for burnishing is set in the range of 10 μm to 20 μm, a highly accurate machining shape can be obtained. This is because, when the diameter difference δ is smaller than 10 μm, the convex portion of the inner surface of the hole 105b cannot be crushed so much, and the unevenness still exists on the inner surface of the hole 105b (mounting hole 105) after burnishing. This is because a good machining accuracy cannot be obtained. On the other hand, when the diameter difference δ is larger than 20 μm, the portion of the blade portion 20 for burnishing that contacts the convex portion of the inner surface of the hole 105b becomes large, the resistance during burnishing increases, and the tool 1 chatters. The problem is that vibration tends to occur or the convex portion of the inner surface of the hole 105b is peeled off, and high machining accuracy cannot be obtained, or the tool 1 moves from one opening of the hole 105b toward the opening on the opposite side. When moving in 105b, the convex part of the inner surface of the hole 105b is pushed toward the opening on the opposite side by the blade part 20 for burnishing and pushed out from the opening, and the edge of the opening This is because there is a problem that burrs are generated and the deburring process is increased.

  Moreover, the rotary tool 1 for hole drilling has a TiN coating on the whole, and can be made more excellent in terms of welding resistance, heat resistance, wear resistance, and the like.

  Further, when the mounting hole 105 of the universal joint yoke 103 in which the notch 104a is formed in the facing portion 104 as shown in FIG. 6 is machined, a hole having a C-shaped cross section is machined when the hole of the notch 104a is machined. Since this results in intermittent cutting, that is, the cutting resistance increases at the machining start portion of the C-shaped section of the hole and the tool easily escapes, so a normal reamer machining tool performs machining with high accuracy. In the hole machining rotary tool 1 of this example, the machining start portion of the hole end portion having a C-shaped cross section is formed by the front flank 22 of the blade portion 20 for burnishing during burnishing. However, since the resistance does not increase so much and the tool 1 is difficult to escape, the mounting hole 105 can be finished with high accuracy. Moreover, the tool 1 is stabilized because the blade part 20 for burnishing passes through the inside of the mounting hole 105, and good finishing accuracy is obtained for a hole part having a C-shaped cross section.

  As described in detail above, according to the drilling rotary tool 1 of this example, it is possible to form a hole with high machining accuracy by the workpiece. Incidentally, the mounting hole 105 of the universal joint yoke 103 shown in FIG. 6 is machined by using a normal reamer machining tool and the hole machining rotary tool 1 of this example, respectively, and the roundness and surface roughness (Ra ) Was measured and it was as shown in FIG. From this FIG. 5, it is clear that the roundness and the surface roughness (Ra) are greatly improved by machining with the hole drilling rotary tool 1 of this example. If 1 is used, it can be said that a hole can be processed with high accuracy.

  Further, if the universal joint yoke 103 is manufactured using the hole drilling rotary tool 1, the hole drilling rotary tool 1 enables processing with higher machining accuracy. A highly accurate mounting hole 105 can be formed by the facing portion 104.

  As mentioned above, although one Embodiment of this invention was described, the specific aspect which this invention can take is not limited to this at all.

  In the above example, the blade portion 10 for reaming and the blade portion 20 for burnishing are formed in a straight blade shape, but the present invention is not limited to this, and may be formed in a twisted blade shape. The TiN coating only needs to be applied to at least the burnishing blade 20, and is not necessarily applied to the entire drilling rotary tool 1.

  In the above example, the universal joint yoke 103 is taken as an example of the processing object of the hole drilling rotary tool 1, but the workpieces that can be processed by the hole drilling rotary tool 1 of this example are not limited. Is not to be done.

It is the front view which showed schematic structure of the rotary tool for drilling which concerns on one Embodiment of this invention. It is a bottom view of the arrow A direction in FIG. FIG. 3 is a detailed view of part B in FIG. 2. It is explanatory drawing for demonstrating the manufacturing method of the universal joint yoke based on this embodiment. It is the figure which showed the processing precision at the time of processing the attachment hole of the yoke for universal joints using the rotary tool for hole processing concerning this embodiment, and the tool for normal reaming, respectively. It is the top view which showed schematic structure of the universal joint. It is the front view which showed schematic structure of the burnishing drill which concerns on a prior art example. It is a bottom view of the arrow C direction in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotating tool for hole drilling 10 Blade part for reaming 11 Rake face 12 Flank 13 Cutting edge 14 Land 15 Blade groove 16 Chamfer 20 Cutting edge 21 Round land 22 Front flank 23 Rear flank 30 Shank part 103 Universal joint yoke 104 Opposing part 105 Mounting hole

Claims (7)

A rotary tool for drilling in which a blade part for reaming, a blade part for burnishing, and a shank part are formed sequentially from the tip side,
The diameter of the reaming blade is smaller than the burnishing blade, and is formed into a stepped shape.
The blade portion for reaming includes a cutting edge,
The burnishing blade has a round land, a front flank connected to the end of the round land in the tool rotation forward direction, and a rear flank connected to the end of the round land in the reverse direction of the tool rotation. A rotary tool for drilling, characterized by comprising:   2. The rotary tool for drilling holes according to claim 1, wherein a clearance angle of the front flank is set within a range of 10 ° to 40 °.   3. The rotary tool for drilling holes according to claim 1, wherein the clearance angle of the rear flank is set within a range of 30 ° to 60 °. 4.   4. The hole drilling rotary tool according to claim 1, wherein the width of the round land is set in a range of 1 mm to 3 mm.   5. The hole drilling rotation according to claim 1, wherein a difference in diameter between the reaming blade portion and the burnishing blade portion is set within a range of 10 μm to 20 μm. tool.   The rotary tool for drilling according to any one of claims 1 to 5, wherein at least the burnishing blade portion is coated with TiN (titanium nitride). A method of manufacturing a universal joint yoke having a pair of facing portions facing each other at a constant interval, the pair of facing portions having a through-hole parallel to the facing direction formed coaxially,
First, a pilot hole is formed in each of the facing portions corresponding to the formation position of the through hole,
Next, the drilling rotary tool according to any one of claims 1 to 6 and the universal joint yoke are arranged such that the axis of the drilling rotary tool and the axis of the through hole to be formed are coaxial. And arranged so as to be spaced from one of the opposing portions,
While rotating the drilling rotary tool about the axis, the one facing part along the axis of the drilling rotary tool until the burnishing blade passes through the lower hole of the other facing part And moving the blade portion for reaming and the blade portion for burnishing processing sequentially through the prepared holes of the one facing portion and the other facing portion,
A method of manufacturing a universal joint yoke, wherein the hole drilling rotary tool is removed by moving the hole drilling rotary tool along the axis thereof in a direction away from the universal joint yoke.

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