JP5593871B2 - Brazing tools - Google Patents

Description

  The present invention relates to a brazing tool in which a blade portion on which a cutting blade is formed is brazed to a shank portion.

  As such a brazing tool, for example, Patent Document 1 includes a cutting blade body portion having a cutting portion and a shaft portion, and a shank portion to which the cutting blade body portion is joined. The part is inserted with a gap, and an insertion hole part for supplying a brazing material to the gap and fixing the shaft part is coaxially connected to the insertion hole part. A fitting hole portion to be fitted is provided, and a shaft portion or a shank portion has been proposed in which a groove portion is formed between the insertion hole portion and the fitting hole portion. .

JP 2001-105230 A

  By the way, in such a brazing tool, an end mill that performs cutting and the like by forming cutting blades at the tip and outer peripheral portions of the blade and feeding them in a direction intersecting the axis while rotating around the axis. Of course, even a tool such as a drill that drills by forming a cutting blade only at the tip of the blade and feeding it in the axial direction while rotating around the axis. It is inevitable that bending occurs. In addition, minute bending is generated in the blade portion by vibration during cutting.

  The stress due to this bending is the most in the portion of the brazing shaft portion of the blade portion brazed to the shank portion that is located at the opening of the brazing hole portion of the shank portion into which the brazing shaft portion is inserted. growing. However, in the conventional brazing tool described in Patent Document 1, a certain gap (clearance) is provided between the insertion hole and the shaft located in the insertion hole. In addition, since the inner and outer diameters are respectively constant, if this clearance is small, stress may concentrate on the brazed shaft portion at the portion of the brazed hole portion located at the opening, and the blade portion may be broken. is there.

  On the other hand, if the clearance is increased in order to reduce the stress and vibration on the blade and prevent such breakage, the brazing accuracy of the blade to the shank will be impaired and the coaxiality and parallelism will be reduced. As a result, the blade part may be shaken during the cutting process, and the cutting accuracy is also lowered. In addition, when the clearance is thus large, a large amount of brazing material is required for brazing the blade, and the tool becomes expensive when the brazing material is expensive silver brazing.

  The present invention was made under such a background, while maintaining high brazing accuracy with respect to the shank portion of the blade portion, while preventing stress and vibration to the blade portion and preventing breakage thereof, It aims at providing the brazing tool which can prevent that a tool becomes expensive.

In order to solve the above-described problems and achieve such an object, the present invention provides a brazing tool in which a blade portion on which a cutting blade is formed and a shank portion are joined by brazing. A brazing shaft portion is formed at the rear end portion, and a brazing hole portion into which the brazing shaft portion is inserted and brazed is formed at the front end portion of the shank portion. An enlarged diameter portion having an inner diameter larger than that of the rear end side portion of the brazing hole is formed on the distal end side of the portion, and a radial clearance from the brazing shaft portion at the opening of the enlarged diameter portion Is at least four times the radial clearance with the brazing shaft portion at the rear end side portion of the brazing hole portion, and the depth of the enlarged diameter portion from the opening portion of the brazing hole portion Is less than 1/4 with respect to the depth of the brazing hole. Characterized in that it is more than twice the radius clearance in the rear end portion of the brazed hole.

  Therefore, in the brazing tool configured as described above, the brazing accuracy of the blade portion with respect to the shank portion is high by setting the clearance between the rear end side portion of the brazing hole portion and the brazing shaft portion to an appropriate size. The accuracy can be maintained. An enlarged diameter portion having an inner diameter larger than that of the rear end portion to which an appropriate clearance is provided is formed on the front end side of the brazing hole portion, and the brazed hole portion and the brazing hole portion are brazed in the enlarged diameter portion. Since a brazing material having a lower hardness than the hard metal material constituting the blade portion or the shank portion is interposed between the shaft portion and the blade portion, it is possible to absorb the bending and vibration of the blade portion. This stress can be relieved at the opening of the brazing hole where the stress due to the bending of the portion concentrates, and the blade portion can be prevented from being broken. Further, since the enlarged diameter portion having a large inner diameter is formed only around the opening on the tip side of the brazing hole portion, a large amount of brazing material is not required.

  However, if the inner diameter of the enlarged diameter portion is too small, the clearance with the brazed shaft portion may be reduced, and sufficient stress relaxation may not be achieved. In addition, even if the depth of the enlarged diameter portion from the opening portion of the brazing hole is too small, sufficient stress relaxation cannot be achieved in the same manner. When the ratio of the enlarged diameter portion having a large clearance is increased, there is a risk of hindering the maintenance of brazing accuracy.

For this reason, the radial clearance with the brazing shaft portion at the opening of the enlarged diameter portion is four times or more than the radial clearance with the brazing shaft portion at the rear end side portion of the brazing hole portion. In addition, the depth of the enlarged diameter portion from the opening of the brazing hole is ¼ or less of the depth of the brazing hole, and the brazing hole in the rear end side portion of the brazing hole It is set to be twice or more of the radial clearance with the attached shaft portion .

  The enlarged diameter portion may have a cylindrical inner peripheral surface having a constant inner diameter, but stress concentration increases on the opening side of the brazing hole portion. The inner diameter of the expanded portion may be gradually increased toward the distal end, or may be constant after the inner diameter is gradually increased toward the distal end. . In these cases, less brazing material is required.

  As described above, according to the present invention, the blade portion can be brazed to the shank portion with high accuracy, thereby making it possible to achieve high accuracy in cutting and bending to the brazed shaft portion. Therefore, it is possible to prevent the occurrence of breakage and the like by preventing the stress concentration due to, and to extend the tool life.

It is a partially broken side view which shows one Embodiment of this invention. It is an expanded sectional view of the brazing hole part of embodiment shown in FIG. It is an expanded sectional view of the brazing hole part tip side which shows the 1st modification of embodiment shown in FIG. It is an expanded sectional view of the brazing hole part tip side which shows the 2nd modification of embodiment shown in FIG. It is an expanded sectional view of the brazing hole part tip side which shows the 3rd modification of embodiment shown in FIG. It is an expanded sectional view of the brazing hole part front end side which shows the 4th modification of embodiment shown in FIG.

  1 and 2 show an embodiment of the present invention. This embodiment shows a case where the present invention is applied to a brazing type drill, and the tool body 1 includes a shank portion 2 on the rear end side (right side in FIG. 1) and a front end side (in FIG. 1). The brazing shaft portion 5 on the rear end side of the blade portion 3 is inserted into the brazing hole portion 4 formed at the front end portion of the shank portion 2 and brazed by the brazing material 6. By being attached, the shank part 2 and the blade part 3 are joined and integrated coaxially with respect to the tool axis O.

  The outer shape of the shank portion 2 is substantially cylindrical with the tool axis O as the center, and the brazing hole portion 4 is also circular in cross section with the tool axis O as the center. And extends to the rear end side in the tool axis O direction. The brazed hole 4 has a constant inner diameter that allows the rear end side portion 4A to have a clearance that allows the brazed shaft portion 5 of the blade 3 to be inserted into the brazed hole portion 4, and is thus set to a constant inner diameter. An enlarged diameter portion 7 having an inner diameter larger than the inner diameter of the rear end side portion 4A is formed on the front end side of the end side portion 4A.

  Here, in the present embodiment, the enlarged diameter portion 7 has a constant inner diameter larger than the rear end side portion 4A of the brazing hole portion 4 having a constant inner diameter as shown in FIG. 2 has a counterbore shape formed so as to open to the front end surface of the two. Therefore, between the enlarged diameter portion 7 and the rear end side portion 4A of the brazing hole portion 4, it will be directed toward the front end side. A step surface is formed so that the inner diameter of the attachment hole portion 4 is expanded by one step. In the present embodiment, the step surface is a flat annular surface perpendicular to the tool axis O.

  On the other hand, the blade portion 3 of the present embodiment has an outer shape that is substantially cylindrical with the tool axis O as the center, and the outer diameter is larger than the inner diameter of the rear end side portion 4A of the brazing hole portion 4. Is slightly reduced to a constant outer diameter along the direction of the tool axis O. However, a pair of chip discharge grooves 3 </ b> A are used symmetrically with respect to the tool axis O on the outer periphery of the distal end portion of the blade portion 3 in the present embodiment, which is a drill, from the front end flank to the rear end side. The cutting edge 3B is formed at the intersecting ridge line portion between the wall surface facing the tool rotation direction of the chip discharge groove 3A and the tip flank surface. Yes.

  The chip discharge groove 3A formed on the outer periphery of the tip portion of the blade portion 3 is rounded up to the outer peripheral side before the shank portion 2 in a state where the blade portion 3 is brazed to the shank portion 2. The brazing shaft portion 5 on the rear end side of the blade portion 3 inserted into the brazing hole portion 4 including the enlarged diameter portion 7 has a cylindrical shape with the constant outer diameter. Then, the brazing shaft portion 5 is inserted into the brazing hole portion 4 in this manner, and the brazing shaft portion 5 is in contact with the bottom surface of the brazing hole portion 4 in the state where the brazing shaft portion 5 is in contact with the brazing hole portion 4. The brazing material 6 is joined as described above.

  Here, with respect to the brazing shaft portion 5 having a constant outer diameter in this way, the inner diameter of the brazing hole portion 4 is brazed at the opening to the front end surface of the shank portion 2 of the enlarged diameter portion 7 as shown in FIG. The radial clearance A with the shaft portion 5 is four times or more the radial clearance C with the brazing shaft portion 5 in the rear end side portion 4A of the brazing hole portion 4. However, since the brazing shaft portion 5 may be eccentric within the range of the clearance C in a brazed state, the inner diameter (diameter) of the enlarged diameter portion 7 in the opening and the outer diameter of the brazing shaft portion 5 The difference from the (diameter) may be four times or more the difference between the inner diameter (diameter) of the rear end side portion 4A of the brazing hole portion 4 and the outer diameter (diameter) of the brazing shaft portion 5. .

  Further, the depth B of the enlarged diameter portion 7 from the opening to the stepped surface of the enlarged diameter portion 7 of the brazed hole portion 4 is the depth L of the entire brazed hole portion 4 including the enlarged diameter portion 7, That is, the depth is set to 1/4 or less with respect to the depth from the opening of the enlarged diameter portion 7 to the bottom surface of the brazing hole 4 in the rear end side portion 4A, and the rear end side of the brazing hole 4 The clearance 4 in the portion 4A is at least twice as large as the clearance C in the radial direction from the brazing shaft portion 5.

  In the brazing tool configured as described above, the enlarged diameter portion 7 having an inner diameter larger than that of the rear end side portion 4A of the brazing hole 4 is formed on the front end side of the brazing hole 4. Even if the blade portion 3 is bent due to a cutting load acting on the cutting blade 3B of the blade portion 3 at the time of cutting, stress due to such bending is concentrated on the blade portion 3 at the opening of the brazing hole portion 4. Can be prevented. Moreover, the vibration of the blade part 3 at the time of cutting can also be relieved.

  That is, by forming such an enlarged diameter portion 7, the clearance A with the brazing shaft portion 5 on the distal end side of the brazing hole portion 4 in the enlarged diameter portion 7 is the clearance C of the rear end side portion 4A. Bigger than. Since the brazing material 6 such as silver brazing is usually softer than the hard metal material constituting the blade portion 3 and the shank portion 2, the brazing material 6 of the enlarged diameter portion 7 having such a large clearance A is used. The bending and vibration of the blade portion 3 can be absorbed to prevent stress concentration.

  However, the brazing material 6 in the enlarged diameter portion 7 does not necessarily have to be filled so as to be flush with the front end surface of the shank portion 2 as shown in FIG. 2, for example, from the step surface to the front end side. The blade portion 3 may be filled up to the middle of the front end surface of the shank portion 2, and conversely, the blade portion 3 may be brazed so as to rise slightly from the front end surface of the shank portion 2.

  On the other hand, in the brazing tool having the above structure, the rear end side portion 4A of the brazing hole portion 4 has an inner diameter smaller than that of the enlarged diameter portion 7, and accordingly, the clearance C with the brazing shaft portion 5 is also reduced. As a result, the inner diameter of the entire brazing hole 4 is increased, whereas the eccentricity and inclination of the brazing shaft 5 are prevented, and the blade 3 has a high degree of coaxiality and parallelism with respect to the shank 2. Accuracy can be ensured. Further, the amount of expensive brazing material 6 such as silver brazing required for brazing can also be reduced.

  Therefore, according to the brazing tool having the above-described configuration, it is possible to perform high-precision cutting, to prevent breakage of the blade portion 3 due to stress concentration, and to ensure a long life. Costs can also be reduced.

In addition, when the clearance A with the brazing shaft portion 5 in the enlarged diameter portion 7 is too small or the depth B of the enlarged diameter portion 7 is too small, such a stress relaxation effect can be sufficiently achieved. There is a risk of disappearing. Therefore, the clearance A in the radial direction at the opening of the enlarged diameter portion 7 is set to be four times or more the radial clearance C at the rear end side portion 4A of the brazing hole portion 4 as in the present embodiment. The depth B of the diameter portion 7 is set to be twice or more the radial clearance C of the rear end side portion 4A .

However, if the depth B of the enlarged diameter portion 7 becomes too deep, the rear end side portion 4A of the brazing hole 4 may be shortened in the direction of the tool axis O, leading to a reduction in brazing accuracy. Therefore, it is set to 1/4 or less with respect to the depth L of the brazing hole 4 . The radial clearance A of the enlarged diameter portion 7 may be large, but is determined by the outer diameter of the tip surface of the shank portion 2.

  The enlarged diameter portion 7 in the present embodiment has a constant inner diameter larger than the rear end side portion 4A of the brazing hole portion 4 as described above, and the cylindrical inner peripheral surface has a stepped surface. However, the stress due to the bending of the blade 3 is concentrated on the shank portion 2 of the brazing hole 4. Since it is an opening part in a front end surface, the radial direction clearance A with the brazing shaft part 5 should just fully be ensured by this opening part.

  Therefore, for example, as in the first modification of the above embodiment shown in FIG. 3, the inner peripheral surface of the enlarged diameter portion 7 is chamfered as a concave conical surface having a center line on the tool axis O, or in FIG. As shown in the second modification, the inner peripheral surface of the enlarged diameter portion 7 has a concave curve shape that is recessed toward the outer peripheral side of the shank portion 2 in the cross section along the tool axis O, or conversely, Although omitted, the section along the tool axis O is formed in a convex curve shape that protrudes toward the inner peripheral side of the shank portion 2 so that the inner diameter of the enlarged diameter portion 7 gradually increases toward the distal end side. It may be made. In these cases, the amount of the brazing material 7 can be further reduced. In these modified examples shown in FIGS. 3 to 6, the same reference numerals are assigned to portions common to the above-described embodiment, and description thereof is omitted.

  Further, after combining these modified examples and the above-described embodiment, after the inner diameter of the enlarged diameter portion 7 gradually increases toward the distal end side as in the third and fourth modified examples shown in FIGS. It may be made constant. In the third modified example shown in FIG. 5, the inner peripheral surface of the enlarged diameter portion 7 is a shank in the cross section along the tool axis O on the rear end side portion 4A side of the brazing hole portion 4 as in the second modified example. A concave curved shape that is concave on the outer peripheral side of the portion 2 and a cylindrical surface shape having a constant inner diameter are formed on the opening side of the brazing hole portion 4 as in the embodiment.

  Moreover, in the 4th modification shown in FIG. 6, the said embodiment and 1st modification are combined, and the internal peripheral surface of the enlarged diameter part 7 is on the tool axis line O toward the front end side from 4 A of rear end parts. After the inner diameter is gradually increased in a chamfered shape having a conical surface at the center, the inner diameter is set to a constant inner diameter larger than that of the rear end side portion 4A, and is opened at the front end surface of the shank portion 2. Of course, the above embodiment may be combined with a modified example in which the cross section is a convex curve.

  Hereinafter, the effect of this invention about the said radial direction clearance A and the depth B of the enlarged diameter part 7 is demonstrated by giving an Example. In this example, in the brazing tool (drill) having the brazing hole portion 4 in which the inner diameter of the enlarged diameter portion 7 is constant according to the above embodiment, the brazing hole portion 4 has a rear end side portion 4A. The radial clearance C and the depth B with the brazing shaft portion 5 of the enlarged diameter portion 7 are constant with the radial clearance C with the brazing shaft portion 5 being 0.1 mm and the depth L being 10.0 mm, respectively. A plurality of brazing tools changed as shown in Fig. 1 were prepared (indicated by circles and double circles in Table 1).

  Further, as a comparison, the radial direction with respect to the brazing shaft portion 5 over the entire length of the depth L (10.0 mm) of the brazing hole portion 4 without providing the enlarged diameter portion 7 in the brazing hole portion 4. The clearance A was made constant at 0.1 mm and the clearance A was made constant at 0.4 mm (those with a triangle mark and a cross mark in Table 1). These are also shown in Table 1.

  And the drilling which is the brazing tool shown in Table 1 was drilled under the same processing conditions, and the tool life was evaluated based on the number of holes that could be drilled. The results are shown in Table 1. In Table 1, double circles can drill more than 75 holes, circles can drill 50 to 74 holes, triangles can drill 20 to 49 holes The cross mark indicates that the number of holes that could be drilled was less than 20. In addition, in the case where a horizontal line is entered in Table 1, tool creation and drilling are not performed.

In these brazing tools, the material of the shank portion 2 is S45C, the material of the blade portion 3 is SKH51, the brazing material is BAg-6 in JIS Z 3261, and the brazing hole portion 4 has a rear end side portion 4A. The radial clearance C with the brazing shaft 5 was 0.1 mm, and the entire depth L of the brazing hole 4 including the enlarged diameter portion 7 was 10.0 mm. The outer diameter (diameter) of the cutting edge 3B of the blade portion 3 is 2.0 mm, the work material is S50C, the machining hole is a through hole with a depth of 5.0 mm, and the rotation speed during drilling is 3000 mm ^{− 1} and feed was applied by applying a load of 1.5 N to the tool body 1 with the blade 3 facing downward.

  From the results in Table 1, first, the depth B of the enlarged diameter portion 7 is 10.0 mm which is the same as the depth L of the brazed hole portion 4, in other words, the enlarged diameter portion 7 is formed in the brazed hole portion 4. Among those having a constant inner diameter, the brazing hole 4 or the enlarged diameter portion 7 and the brazing shaft portion 5 have a radial clearance A of 0.1 mm, and the brazed hole in the one having the enlarged diameter portion 7. In the case where the radial clearance A between the rear end side portion 4A of the portion 4 and the brazing shaft portion 5 is equal to the radial clearance A (the triangular mark in Table 1), 20 holes or more could be drilled, but brazing Stress was concentrated in the opening of the hole 4, and the blade 3 was broken before the number of processed holes reached 50, resulting in a lifetime.

  Similarly, among the ones in which the depth B of the enlarged diameter portion 7 is 10.0 mm, which is the same as the depth L of the brazed hole portion 4, the brazed hole portion 4 or the enlarged diameter portion 7 and the brazed shaft portion 5 In the case where the radial clearance A is increased to 0.4 mm (the cross mark in Table 1), the blade portion 3 is tilted and brazed with respect to the shank portion 2, and this causes the cutting blade to be cut during drilling. A large runout occurred in 3B, and drilling was impossible without reaching 20 holes.

On the other hand, in the brazing tool in which the enlarged diameter portion 7 having an increased inner diameter is formed on the distal end side of the brazing hole portion 4 (the ones in the circles and double circles in Table 1), 50 holes are provided in each case. The above drilling was possible. Of these , the radial clearance A between the brazing shaft portion 5 at the opening of the enlarged diameter portion 7 and the radial clearance C between the brazing shaft portion 5 at the rear end side portion 4A of the brazing hole portion 4 ( 0.1 mm), and the depth B of the enlarged diameter portion 7 from the opening of the brazing hole 4 is equal to the depth L (10. 0 mm) and a brazing tool according to the present invention, which is equal to or less than 2.5 mm, which is 1/4, and 0.2 mm or more, which is twice the radial clearance C in the rear end side portion 4B of the brazing hole 4. With the double circles shown in Table 1, it was possible to perform highly accurate drilling without causing breakage or the like even when processing 75 holes or more.

  Of these, the radial clearance A is 0.4 mm, which is four times the radial clearance C (0.1 mm), and the depth B of the enlarged diameter portion 7 is the depth of the brazing hole 4. For those with 0.2 mm, which is 1/50 with respect to L (10.0 mm) and twice the radial clearance C, the enlarged-diameter portion 7 has a counterbore shape as in the above embodiment. Even in the case of a chamfered shape in which the inner peripheral surface of the enlarged diameter portion 7 is a concave conical surface as in the first modification shown in FIG. 3, drilling was performed under the same conditions. As a result, as shown in Table 1, 75 or more holes could be drilled.

DESCRIPTION OF SYMBOLS 1 Tool body 2 Shank part 3 Blade part 3B Cutting blade 4 Brazing hole part 4A Brazing hole part 4 Rear end side part 5 Brazing shaft part 6 Brazing material 7 Expanded part O Tool axis A Opening of expanded part 7 Clearance in the radial direction with the brazing shaft portion 5 at the portion B Depth of the enlarged diameter portion 7 from the opening of the brazing hole portion 4 C With the brazing shaft portion 5 at the rear end side portion 4A of the brazing hole portion 4 Radial clearance L Depth of brazing hole 4

Claims (4)

A brazing tool in which a blade portion on which a cutting edge is formed and a shank portion are joined by brazing, wherein a brazing shaft portion is formed at a rear end portion of the blade portion, and a tip portion of the shank portion A brazing hole portion into which the brazing shaft portion is inserted and brazed is formed in the brazing hole portion, and the inner diameter of the brazing hole portion is larger than that of the rear end side portion of the brazing hole portion. An enlarged diameter portion is formed, and a radial clearance with the brazed shaft portion at the opening of the enlarged diameter portion is a radius with the brazed shaft portion at the rear end side portion of the brazed hole portion. The brazing hole is at least four times the directional clearance, and the diameter of the enlarged diameter portion from the opening of the brazing hole is ¼ or less of the depth of the brazing hole. 2 of the radial clearance at the rear end portion of the attachment hole Brazed tool, characterized in that there is a higher. The brazing tool according to claim 1 , wherein an inner diameter of the enlarged diameter portion is constant. The brazing tool according to claim 1 , wherein the inner diameter of the enlarged diameter portion gradually increases toward the tip side. The brazing tool according to claim 1 , wherein the inner diameter of the enlarged diameter portion is constant after gradually increasing toward the tip side.

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