JP2005118940A - Deep hole cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance cutting efficiency by improving discharge performance of chips by a coolant supplied via the intermediate inside, by sufficiently securing strength of a recess-projection connecting part, when using a cutting head having a plurality of cutting edges, with a tool shank and the cutting head as a separate member, in a deep hole cutting tool applied to a gun drill system. <P>SOLUTION: One discharge groove 7 and 2 continuing in a straight line shape with a discharge groove in the longitudinal direction of the tool shank 3, is arranged on an outer peripheral surface of the cutting head 5. A bypass flow passage hole 9 is formed so as to reach the discharge groove 7 by passing through the head inside from a tip part of the cutting head 5. The plurality of cutting edges 10a to 10c are distributively formed by respectively facing to the discharge groove 7 and a discharge port 8 on the bypass flow passage hole 9 side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a deep hole cutting tool such as a drill applied to a gun drill system.

  As a deep hole drilling system, a gun drill system, a BTA system, an ejector system, and the like are known, but a gun drill system with a simple configuration is widely used for drilling a relatively small diameter deep hole.

  As shown in FIG. 13, the gun drill system includes a gun drill 30 in which a cutting head 32 is integrally fixed to the tip of a tool shank 31 having a hollow cylindrical shape and having a V-shaped groove in the longitudinal direction on the outer surface. The hollow portion of the tool shank 31 is used as the supply passage 33 for the coolant C, and the concave groove is used as the discharge groove 34 for the chips S. During deep hole machining, the high-pressure coolant C is discharged from the tip side of the cutting head 32 through the supply passage 33. The chips S generated in the cutting hole H of the workpiece W are discharged to the outside through the discharge groove 34 together with the coolant C. Therefore, this gun drill system has an advantage that the chip S can be discharged relatively easily by making the space of the discharge groove 34 large even with a small diameter.

  By the way, as a tool with an oil hole used for drilling a relatively large diameter, a drill having a plurality of cutting blades is widely used. Therefore, since such a plurality of cutting blades are arranged so that their directions are opposite to each other on both sides in the radial direction of the drill tip, when using a cutting head having a plurality of cutting blades in a gun drill system, In order to efficiently discharge the chips, discharge grooves having a V-shaped cross section along the longitudinal direction are provided on both sides in the radial direction of the tool shank and the cutting head.

  For example, FIG. 12 shows a hypothetical configuration in which a cutting head having three cutting edges applied to a gun drill system is used as a separate member from the tool shank, (A) is the head front end surface, and (B) is the base end. It is a cross section of the screw engaging part (male thread part) of the side. As shown in the figure, the cutting head 32 has large and small discharge grooves 35 and 36 having a V-shaped cross section on both sides in the radial direction, and at one end of the large discharge groove 35 (cutting head rotation) at the tip of the cutting head. The peripheral cutting edge 37a and the central cutting edge 37b are provided facing the side surface in the direction rear side), and the intermediate cutting edge 37c facing the side surface on the same side of the small discharge groove 36 (the rear side in the rotation direction of the cutting head). The coolant supply holes 40 and 41 are respectively penetrated through the substantially fan-shaped meat portions 38 and 39 on both sides separated by the constriction by both the discharge grooves 35 and 36, and each of the supply holes 40 and 41 is formed at the front end surface of the head. The discharge ports 42 and 43 are opened. Reference numeral 44 denotes a guide pad fixed to the outer peripheral surfaces of the meat portions 38 and 39.

  Thus, in such a cutting head 32, the region of the male screw 45 in the screw engaging portion on the proximal end side is cut out by the two discharge grooves 35 and 36 into two arc portions as shown in FIG. In addition to the separation, the two arc portions are only slightly more than half of the entire circumference, and naturally the area of the female thread (not shown) of the corresponding screw engaging portion on the tool shank side is the same. Become. Therefore, in the deep hole cutting tool in which the cutting head 32 is connected to the tool shank by screw engagement, the strength of the connecting portion between the two becomes very weak, and the connecting portion is broken, bent or twisted by a cutting load. Deformation easily occurs.

  In view of the circumstances described above, the present invention has a configuration in which a tool shank and a cutting head are connected as separate members, and the cutting head is provided with a plurality of cutting blades. It is an object of the present invention to provide a deep hole cutting tool that can sufficiently secure the strength of the cutting head and the connecting portion, improve the chip dischargeability, and increase the cutting efficiency.

  In order to achieve the above object, the deep hole cutting tool according to claim 1 of the present invention is provided with the reference numeral shown in the embodiment, and the hollow interior is used as the coolant supply passage 1, and the longitudinal direction of the outer peripheral surface is set. A tool shank 3 having a single discharge groove 2 having a V-shaped cross section formed along the cutting head, and a base end portion of the tool shank 3 detachably connected to the tip end portion of the tool shank 3 coaxially by a concavo-convex connecting portion 4. The cutting head 5 includes a coolant supply hole 6 communicating with the coolant supply passage 1 of the tool shank 3 in a connected state, and one discharge groove linearly connected to the discharge groove 2 of the tool shank 3. 7, a discharge port 8 opened from the front end surface to the outer peripheral surface at a position substantially opposite to the discharge groove 7 in the radial direction, and a bypass flow path hole extending from the discharge port 8 to the discharge groove 7 through the inside of the head 9 and the cutting head A plurality of cutting blades 10a, 10b, and 10c are distributed and formed at the front end portion of the discharge groove 7 and the discharge port 8, respectively, and two discharge ports communicating with the coolant supply hole 6 on the front end surface. A configuration is adopted in which the outlets 11a and 11b are opened at substantially opposite positions in the radial direction.

  According to the deep hole cutting tool having the above configuration, since the discharge grooves 2 and 7 having a V-shaped cross section formed along the longitudinal direction on the outer peripheral surfaces of the tool shank 3 and the cutting head 5 are one, The region of the connecting portion 4 is notched at one place in the circumferential direction by the discharge grooves 2 and 7 and has a shape that is continuous in the circumferential direction over approximately 3/4. Therefore, the uneven connecting portion 4 of the tool shank 3 and the cutting head 5 is provided with sufficient strength to withstand the cutting load, and is difficult to be deformed such as breakage, bending or twisting during processing. Thus, there is one discharge groove 2 and 7, and the chips cut by the cutting blades 10a and 10b on one side facing the discharge groove 7 remain as they are with the coolant discharged from the discharge port 11a at the tip. Although it is discharged through the discharge groove 7, the chips cut by the other cutting edge 10c also flow into the discharge groove 7 through the bypass channel 9 together with the coolant discharged from the discharge port 11b. It is discharged through the discharge grooves 7 and 2, so that a high cutting efficiency based on good chip discharge is obtained.

  Moreover, according to the deep hole cutting tool which concerns on Claim 2, the said uneven | corrugated connection part 4 has the concave step part 14 or the convex step part 15 on one outer peripheral surface of the both connection end parts 12 and 13 connected mutually. A projecting step portion that is provided around the inner peripheral surface of the other connecting end portion 13 that is externally fitted to the one connecting end portion 12 and that is inlay-fitted to the concave step portion 14 to prevent both axial movements. The rotation preventing means 16 for blocking the relative rotation of the both is provided between the connecting end portions 12 and 13 and the rotation preventing means 16 is provided between the connecting end portions 12 and 13. .

  Further, according to the deep hole cutting tool of the third aspect, the rotation preventing means 16 is a key provided so as to protrude in the radial direction from either one of the connecting end portions 12 and 13. 17 and a key groove 18 provided in the other connecting end 12 so as to receive the key 17, the structure according to claim 1 or 2.

  Further, according to the deep hole cutting tool according to claim 4, the rotation preventing means 16A includes the screw hole 19 that penetrates the connecting end portion 13 in the radial direction from one outer peripheral surface of both the connecting end portions 12 and 13. The side lock screw 20 is screwed into the screw hole 19 and the tip end portion is pressed against the outer peripheral surface of the other connecting end portion.

  Further, according to the deep hole cutting tool according to claim 5, the rotation preventing means 16B is a key provided so as to protrude in the radial direction from either one of the connecting end portions 12 and 13. 17 and the key groove 18 provided in the other connecting end 12 so as to receive the key 17, the screw hole 19 penetrating the connecting end 12 in the radial direction from the outer peripheral surface of the one connecting end 13, and this The structure according to claim 1 or 2, comprising a side lock screw 20 that is screwed into the screw hole 19 and whose tip is pressed against the outer peripheral surface of the other connecting end.

  Moreover, according to the deep hole cutting tool which concerns on Claim 6, discharge port 11a, 11b opened to the front end surface of the said cutting head 5 is the front-end | tip open part of the said discharge groove 7 via coolant guidance recessed part 21a, 21b. It consists of a structure in any one of Claims 1-5 connected to.

  As described above, the discharge ports 11a and 11b that open to the front end surface of the cutting head 5 are connected to the front end open portion of the discharge groove 7 via the coolant guide recesses 21a and 21b, thereby being discharged at the front end portion of the head. Therefore, the chips generated from the cutting blades 10a, 10b, 10c facing each other can be efficiently discharged together.

  Further, according to the deep hole cutting tool according to claim 7, the cutting head 5 includes a central cutting edge 10b and a peripheral cutting edge 10a on the discharge groove 7 side, and an intermediate part on the bypass flow path hole 9 side. The cutting blade 10c has a configuration according to any one of claims 1 to 6, which is formed respectively.

  As a result, the chips flow directly into the discharge groove 7 on the discharge groove 7 side at the front end of the head 5, while the chips join the discharge groove 7 via the curved flow path on the bypass flow path hole 9 side. This is because there is a difference in dischargeability due to flow resistance between them, and it is preferable that the amount of generated chips is increased on the discharge groove side with higher dischargeability.

  According to the first aspect of the present invention, in the configuration in which the tool shank to which the gun drill system is applied and the cutting head are connected as separate members and the both are connected by the concave-convex connecting portion, a depth using a cutting head provided with a plurality of cutting edges is used. As a hole cutting tool, a tool shank and one discharge groove linearly connected to the tool shank discharge groove are provided on the outer peripheral surface of the tool shank and the cutting head, and the cutting head reaches the discharge groove from the tip through the inside of the head. By providing a bypass channel hole and distributing and forming a plurality of cutting blades facing the discharge groove and the discharge port on the bypass channel hole side, the strength of the tool shank, the cutting head, and the connecting portion is sufficiently increased. It is possible to ensure the cutting efficiency by improving the chip discharging performance by the coolant.

  According to the deep hole cutting tool of the invention according to claim 2, in place of the conventional screw-type connection structure, a concave step portion or a convex step portion is provided around one outer peripheral surface of both connection end portions, On the inner peripheral surface of the other connecting end portion fitted on the connecting end portion, a convex step portion or a concave step portion is provided around the concave step portion so as to prevent both axial movements by fitting with the concave step portion, and Since the rotation preventing means for preventing the relative rotation of both is interposed between the connecting end portions, there is no problem of overtightening as in the case of the screw type connecting structure, and the rear end portion of the drill head and the tip end portion of the shank Can be properly connected.

  According to the invention of claim 3, the rotation preventing means is provided on the key provided so as to protrude in the axial direction from either one of the two connecting ends, and provided on the other connecting end so as to receive the key. In the case where the key groove is formed, both the connecting end portions to be connected are not damaged, and the relative rotation of both can be easily and reliably prevented.

  According to the invention of claim 4, the rotation preventing means is screwed into the screw hole that penetrates the connecting end portion in the radial direction from one outer peripheral surface of both connecting end portions, and the tip thereof. If the part consists of a side lock screw that is pressed against the outer peripheral surface of the other connection end, it is only necessary to make a screw hole on one connection end and screw the side lock screw into this. Becomes easy.

  According to the invention of claim 5, the rotation preventing means is provided at the other connecting end portion so as to receive the key provided so as to protrude in the axial direction from either one of the two connecting end portions. A key groove, a screw hole that penetrates the connecting end portion in the radial direction from the outer peripheral surface of one connecting end portion, and a side lock screw that is screwed into the screw hole and has its tip pressed against the outer peripheral surface of the other connecting end portion In this case, the relative rotation of the two connected to each other can be more reliably prevented.

  According to the invention of claim 6, in the deep hole cutting tool described above, between the tip opening portion of the discharge groove and the coolant discharge port located on the front side in the head rotation direction on the tip surface of the cutting head, and A coolant guide recess is formed between the discharge port and the discharge port located on the front side in the head rotation direction, so that the coolant discharged from the head tip is discharged to the discharge groove and bypass channel hole. Therefore, the chips generated from the cutting blades facing each other can be efficiently discharged together.

  According to the invention of claim 7, in the deep hole cutting tool having a cutting head having three cutting edges, a central cutting edge and a peripheral cutting edge and an intermediate cutting edge, on the discharge groove side of the cutting head. The peripheral cutting edge and the central cutting edge are arranged on the bypass channel hole side, and the intermediate cutting blade is disposed on the bypass channel hole side, so that the chips flowing in according to the difference in dischargeability between the discharge groove and the bypass channel hole The amount is balanced and high chip discharge is ensured as a whole.

  Preferred embodiments of the deep hole cutting tool according to the present invention will be specifically described below with reference to the drawings. FIGS. 1A and 1B show a gantry cutting head 5, and FIGS. 2A and 2B show a tool shank 3. 1 (a) and 1 (b), a coolant supply hole 6 is formed at the center of the cutting head 5, and is bifurcated midway and connected to the branch flow paths 22a and 22b. The cutting head 5 has a fan-shaped cross section of approximately 110 ° as shown in (b) and is formed with a single straight discharge groove 7 in the axial direction. As shown in (b), the discharge groove 7 A discharge port 8 opened from the front end surface to the outer peripheral surface at a substantially opposite position in the radial direction is formed, and a bypass passage hole 9 extending from the discharge port 8 through the inside of the cutting head 5 to the discharge groove 7 is formed. (See FIGS. 3, 6, 7, and 8).

  A plurality of cutting blades 10a, 10b, and 10c are distributed and formed at the front end of the cutting head 5 so as to face the discharge groove 7 and the discharge port 8, respectively, and the coolant supply hole 6 is formed on the front end surface. Two discharge ports 11a and 11b that communicate with each other through the branch flow paths 22a and 22b are formed to open at substantially opposite positions in the radial direction.

  A peripheral cutting edge 10a and a central cutting edge 10b made of a cemented carbide tip are screwed to the front end of the cutting head 5 so as to face the side surface of the discharge groove 7 on the rear side in the head rotation direction. The intermediate cutting edge 10c made of a chip faces the discharge port 8 and is screwed in an arrangement opposite to the peripheral cutting blade 10a and the central cutting blade 10b, and is removed from the discharge groove 7 and the discharge port 8. Guide pads 23 are fixed at two locations on the outer periphery. Of the pair of discharge ports 11a and 11b at the tip of the cutting head 5, one discharge port 11a is connected to the discharge groove 7 via the coolant guide recess 21a, and the other discharge port 11b is the coolant guide recess 21b. Is connected to the discharge port 8. The discharge port 11a corresponding to the discharge groove 7 has a larger diameter than the discharge port 11b corresponding to the discharge port 8 and its discharge.

  Further, a concave step portion 14 is provided around the outer peripheral surface of the connecting end portion 12 at the rear portion of the cutting head 5 in the center portion in the axial direction, and the spigot convex portions 24a are provided at both end portions in the axial direction across the concave step portion 14. 24b are provided around. In addition, a key groove 18 having a constant width is formed in the concave step portion 14 in the circumferential direction (see FIGS. 1, 5, 6, 7, 8, 9, 10 (b) and 10 (c)). ).

  As shown in FIGS. 2A, 2B, and 10A, the tool shank 3 has the same fan-shaped cross section as the discharge groove 7 of the cutting head 5 and is linear in the axial direction. One discharge groove 2 is formed, and a coolant supply passage 1 is formed at the center thereof. The coolant supply passage 1 may be formed by inserting the tubular body 1a into a semi-circular cutout section obtained by hollowing out the central portion of the tool shank 3 in the axial direction.

Then, a convex step portion 15 corresponding to the concave step portion 14 of the cutting head 5 and a convex step portion 15 of the cutting head 5 sandwiching the convex step portion 15 at the connecting end portion 13 on the tip end side of the tool shank 3. Inner recesses 25a, 25b corresponding to the portions 24a, 24b are provided around the key, and the key 17 corresponding to the key groove 18 of the cutting head 5 is provided on the convex step 15 in the radial direction (center axis direction) in the axial center. Is protruding. As shown in FIG. 9, the key 17 may be integrally formed by cutting or the like in the convex step portion 15 of the tool shank 3, but a fitting hole is provided in the convex step portion 15 and the key 17 is fitted thereto. And you may make it fix to the connection end part 13 with the screw | thread 17a.
The key 17 and the key groove 18 form a rotation preventing means 16.

  In order to connect the connecting end 12 of the cutting head 5 having the above-described configuration to the connecting end 13 of the tool shank 3, as shown in FIG. 11, the discharge groove 2 of the tool shank 3 faces upward, The connecting end 12 of the cutting head 5 is brought upward with the discharge groove 7 of the cutting head 5 turned sideways as shown in the figure, and the connecting end 12 of the cutting head 5 is moved from the state shown in the figure. As it is lowered, the convex step portion 15 and the spigot concave portions 25a, 25b of the connecting end portion 12 are aligned with the concave step portion 14 of the connecting end portion 13 of the tool shank 3 and the spigot convex portions 24a, 24b in the vertical direction. Then, the tool shank 3 is inserted from the discharge groove 2 toward the center of the tool shank 3.

  As a result, the convex step 15 and the spigot concave portions 25a and 25b of the connecting end portion 12 of the cutting head 5 are properly fitted to the concave step portion 14 and the spigot convex portions 24a and 24b of the connecting end portion 13 of the tool shank 3. Since the key 17 on the tool shank 3 is engaged with the key groove 18 on the cutting head 5 side, the cutting head 5 and the tool shank 3 are relatively rotated in the circumferential direction in this state, and the key 17 is moved to the key groove 18. The concave step portion 14 of the cutting head 5 is turned to the convex step portion 15 of the tool shank 3 and the former spigot convex portions 24a and 24b are made to the latter spigot concave portion 25a. 25b, the concave step portion 14 of the cutting head 5 engages with the convex step portion 15 of the tool shank 3, and the relative movement thereof in the axial direction is prevented. 18 end walls 18a By contact, relative movement in the both circumferential direction is prevented.

  Further, the spigot protrusions 24a and 24b on the cutting head 5 side are properly fitted in the spigot recesses 25a and 25b on the tool shank 3 side to accurately maintain the axial concentricity between the cutting head 5 and the tool shank 3. become.

  Further, the discharge groove 7 on the cutting head 5 side and the discharge groove 2 on the tool shank 3 side coincide with each other in the axial direction at a position where the relative movement in the circumferential direction of both is prevented, and one discharge groove 7, 2. Of course, the coolant supply passage 1 on the tool shank 3 side and the coolant supply hole 6 on the cutting head 5 side are accurately connected.

  Therefore, during the deep hole cutting operation, the cutting head 5 and the tool shank 3 are held together so that an accurate cutting operation can be performed.

  As described above, according to the rotation preventing means comprising the key 17 provided on the tool shank 3 side and the key groove 18 provided on the cutting head 5 side, both the connecting end portions 12 and 13 to be connected are damaged. Therefore, both relative rotations can be easily and reliably prevented.

  As the rotation blocking means 16 according to the present invention, instead of the key 17 and the key groove 18 as described above, as shown in FIG. 8, a radial direction is formed from the outer peripheral surface of the connecting end portion 13 of the tool shank 3. A screw hole 19 penetrating into the screw hole 19 may be provided, and a side lock screw 20 that is screwed into the screw hole 19 and whose tip is pressed against the outer peripheral surface of the connecting end 12 of the cutting head 5 may be used. In this case, an engagement hole 26 that engages the pointed end portion of the side lock screw 20 is provided at a required position on the outer peripheral surface of the coupling end portion 12 of the cutting head 5. According to such rotation prevention means including the side lock screw 20, it is only necessary to open the screw hole 19 on one of the connecting end portions and screw the side lock screw 20 into the screw hole 19, so that the installation work is simplified. .

  The rotation preventing means according to the present invention may be a combination of the key 17 and the key groove 18 and the screw hole 19 and the side lock screw 20 screwed into the screw hole 19 as described above. According to such a combination of the key 17 and the key groove 18, the screw hole 19, and the side lock screw 20, it is possible to more reliably prevent the relative rotation of both connected to each other.

  On the other hand, in this gun drill, since the cutting head 5 is detachable from the tool shank 3, when the cutting blades 10a to 10c of the cutting head 5 are worn out or broken, only the cutting head 5 is replaced. The tool shank 3 can be used continuously as it is, and only the cutting head 5 needs to be screwed and replaced when changing the setup. Therefore, the work can be easily performed in a short time, and the production efficiency is improved. For exchanging in accordance with the consumption of 10c, since only the cutting head 5 can be removed and handled alone, these operations can be easily performed, and also when switching to other cutting operations such as drilling and reaming, the corresponding types of cutting Since only the head needs to be prepared, the equipment cost can be reduced and the replacement work can be easily performed in a short time.

  The discharge grooves 7 and 2 are illustrated with a V-shaped cross section having an opening angle of 110 °, but can be set to an appropriate opening angle in the range of approximately 90 ° to 130 °. In order to improve the strength by increasing the meat part on the center side of 3 and 5, the bottom part may have a slightly protruding round shape. On the other hand, the cutting head may have two or four or more cutting blades in addition to those having three cutting blades 10a to 10c as in the embodiment, and braze the carbide tip of the cutting blade. Alternatively, it is also possible to use a tool in which the entire cutting head is made of tool steel and a cutting edge is directly formed at the tip.

  In the embodiment described above, the concave step portion 14 formed at one place on one outer peripheral surface of both connecting end portions connected to each other and the convex portion formed at one place on the inner peripheral surface of the other connecting end portion. The step portion 15 is inlay-fitted with each other, but the concave step portion 14 and the convex step portion 15 are not limited to one place each, and may be formed at two places or three places, respectively.

  In this embodiment, the concave step portion 14 is formed on the outer peripheral surface side of the connecting end portion 12 on the cutting head 5 side, and the convex step portion 15 is formed on the inner peripheral surface side of the connecting end portion 13 of the tool shank 3. However, the convex step portion 15 may be formed on the outer peripheral surface side of the connecting end portion 12 of the cutting head 5, and the concave step portion 14 may be formed on the inner peripheral surface side of the connecting end portion 13 of the tool shank 3. Further, in the embodiment, the concave step portion 14 and the convex step portion 15 are each formed in a straight shape, but may be formed in a tapered shape.

  In the gun drill having the above-described configuration, since the discharge grooves 2 and 7 having a V-shaped cross section formed along the longitudinal direction are formed on the outer peripheral surfaces of the tool shank 3 and the cutting head 5, the concave and convex connecting portions 4A and 4B of the both are provided. This region is cut out at one place in the circumferential direction by the discharge grooves 2 and 7 and has a shape continuous in the circumferential direction over approximately 3/4. Accordingly, the connecting portion formed by the concave and convex engagement between the tool shank 3 and the cutting head 5 has sufficient strength to withstand the cutting load, and it is difficult for deformation such as breakage, bending and twisting during processing. Thus, the discharge groove 7 of the cutting head 5 is one, but the chips cut by the peripheral cutting edge 10a and the central cutting edge 10b are directly affected by the coolant discharged from the discharge port 11a at the tip. While being discharged through the discharge groove 7 and the discharge groove 2 of the tool shank 3, the chips cut by the intermediate cutting edge 10c are also bypassed through the discharge port 8 together with the coolant discharged from the discharge port 11b. Then, it flows into the discharge groove 7 from the junction 9b and is discharged through the discharge groove 7 and the discharge groove 2 of the tool shank 3. Therefore, according to this gun drill, the high cutting efficiency based on the favorable discharge property of chips can be obtained.

  In this embodiment, the coolant guide recesses 21a and 21b extending from the discharge ports 11a and 11b to the discharge groove 7 and the discharge port 8 are formed on the front end surface of the cutting head 5, so that the discharge is performed at the head end portion. The coolant to be discharged can be distributed to the discharge groove 7 and the bypass flow passage hole 9 without any deviation, so that chips generated from the cutting blades 10a to 10c facing each other can be efficiently discharged together. Further, the peripheral cutting edge 10a and the central cutting edge 10b face the discharge groove 7 side, and the intermediate cutting edge 10c faces the discharge port 8 side, that is, the bypass flow path hole 9 side. While a large amount of chips generated from the center cutting edge 10b flows directly into the discharge groove 7, the intermediate cutting edge 9c is relatively formed on the bypass flow path hole 9 side which is inferior in discharge performance due to a curved flow path flow resistance. A small amount of chips will flow in, and the amount of chips flowing in will be balanced in accordance with the difference in dischargeability between the discharge groove 7 and the bypass passage hole 9, thereby ensuring high chip discharge performance as a whole.

(A) is a front view of the cutting head of the gun drill which concerns on 1st embodiment of this invention, (b) is a side view. (A) is a front view of a tool shank, (b) is a side view. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. It is arrow sectional drawing of the VV line | wire of Fig.1 (a). It is arrow sectional drawing of the VI-VI line of FIG.1 (b). It is arrow sectional drawing of the VII-VII line of FIG.1 (b). It is a front view showing the whole gun drill composition concerning a first embodiment of the present invention. FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 8. (A) is a partially cutaway perspective view of a tool shank. (B) is a partially cutaway perspective view of the cutting head. (C) is also a partially cutaway perspective view of the cutting head viewed from a different visual angle. It is a perspective view explaining the assembly state of a cutting head and a tool shank. (A) is a side view of the cutting head of the conventional gun drill. (B) is a longitudinal side view. It is explanatory drawing which shows the operating state of this kind of gun drill.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coolant supply path 2 Discharge groove 3 Tool shank 4A, 4B Concavity and convexity connection part 5 Cutting head 6 Coolant supply hole 7 Discharge groove 8 Discharge port 9 Bypass flow path hole 10a Peripheral part cutting edge 10b Center part cutting edge 10c Middle part cutting edge 11a Discharge port 11b Discharge port 12 Connection end portion 13 Connection end portion 14 Concave step portion 15 Convex step portion 16 Rotation prevention means 17 Key 18 Key groove 19 Screw hole 20 Side lock screw 21a Coolant guide recess 21b Coolant guide recess

Claims (7)

The hollow shank is used as a coolant supply passage, and the tool shank having one discharge groove having a V-shaped cross section formed along the longitudinal direction of the outer peripheral surface is coaxially connected to the distal end portion of the tool shank by the concave-convex connecting portion. A cutting head that is detachably connected to the shape,
The cutting head includes a coolant supply hole communicating with the coolant supply passage of the tool shank in a connected state, a discharge groove linearly connected to the discharge groove of the tool shank, and a radial direction with respect to the discharge groove. A discharge port opened from the front end surface to the outer peripheral surface at a substantially opposite position, and a bypass flow path hole extending from the discharge port through the inside of the head to the discharge groove,
A plurality of cutting blades are distributed and formed at the tip of the cutting head so as to face the discharge groove and the discharge port, respectively, and two discharge ports communicating with the coolant supply hole are provided on the tip surface in the radial direction. A deep hole cutting tool that opens at a substantially opposite position.   The concave-convex connecting portion has a concave stepped portion or a convex stepped portion around one outer peripheral surface of both connecting end portions that are connected to each other, and the inside of the other connecting end portion that is externally fitted to the one connecting end portion. On the peripheral surface, a convex step portion is provided around the concave step portion so as to prevent both axial movements, and a rotation prevention means for preventing the relative rotation of both is provided between the connecting end portions. The deep hole cutting tool according to claim 1, wherein the deep hole cutting tool is configured to be interposed.   The rotation preventing means includes a key provided so as to protrude in a radial direction from one of the two connecting ends, and a key groove provided in the other connecting end so as to receive the key. The deep hole cutting tool according to claim 1 or 2, comprising:   The rotation preventing means includes a screw hole that penetrates the connecting end portion in a radial direction from one outer peripheral surface of both connecting end portions, and is screwed into the screw hole, and a tip portion thereof is an outer peripheral surface of the other connecting end portion. The deep hole cutting tool according to claim 1, comprising a side lock screw pressed against the deep hole cutting tool.   The rotation preventing means includes a key provided so as to protrude in a radial direction from either one of the connection ends, and a key groove provided in the other connection end so as to receive the key, A screw hole that penetrates the connecting end portion in a radial direction from an outer peripheral surface of one connecting end portion, and a side lock screw that is screwed into the screw hole and has a tip pressed against the outer peripheral surface of the other connecting end portion. Item 3. The deep hole cutting tool according to Item 1 or 2.   The deep hole cutting tool according to any one of claims 1 to 5, wherein a discharge port that opens at a front end surface of the cutting head is connected to a front end open portion of the discharge groove via a coolant guide recess. 7. The cutting head according to claim 1, wherein a center part cutting edge and a peripheral part cutting edge are formed on the discharge groove side, and an intermediate part cutting edge is formed on the bypass channel hole side. Deep hole cutting tool.

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