Boring bar tool

Abstract: A boring bar tool for use with a tip (510) is disclosed which has a tool body (501). The tip (510) being mounted to one side of a forward end of the nose (511). A neck (512) formed at a proximal end of said nose (511) and a shank (513) in the form of a shaft formed at proximal end of said neck (512). The neck (512) has a cross-sectional area in a plane perpendicular to an axis of said shank (513), which is larger than the cross-sectional area of said shank (513) in the plane. A chip-pocket (520) is formed in a forward end of said tool body, wherein a chip-pocket is contiguous to a face of said tip. A first chip-pocket section opening to an outer peripheral surface of said tool body, and a second chip-pocket section (523) which extends along a front cutting edge of said tip and which opens to the outer peripheral surface of said tool body on the side opposite to the side where said first chip-pocket section opens.

Description: The present invention relates to a boring bar tool used to process a bore in cutting processing work. The invention was first disclosed in EP-A-0405443, from which the present application has been divided. In this specification, the invention claimed in parent EP-A-0405443 is identified as "the parent invention". Boring bar tools of the kind referred to above are conventionally known; such tools are shown, for example, in Figs. 46 through 48, Figs. 49 through 51 and Figs. 52 through 54 of the attached drawings and described in detail in EP-A-0405443. DE-B-1074364 discloses a boring bar tool with a shank and a neck but, unlike the prior proposals described above, the diameter of the neck is larger than that of the shank. SUMMARY OF THE INVENTION According to the invention, there is provided a boring bar tool comprising a tip, the boring bar tool having the features recited in at least one of claims 1 and 7 below. Preferably, the neck is formed with shaft-like configuration in which the cross-sectional area of the neck in the plane perpendicular to the axis of the shank is gradually reduced, while not being reduced to a value below that of the cross-sectional area of the shank in the plane, as it approaches the proximal end of the neck from the forward end thereof. A flank is formed on an outer periphery of the neck contiguous to the tip. The flank approaches the axis of the shank as it approaches the proximal end of the neck from the forward end thereof. With the above arrangement, since the cross-sectional area of the neck in the plane perpendicular to the axis of the shank is reduced as it approaches the proximal end of the neck from the forward end thereof, the rigidity of the shank is reduced to a value below that of the forward end of the neck, so that the entire construction of the boring bar tool becomes an elastic or flexible construction in which vibrations differing from each other in accordance with mass or rigidity, in other words, the spring constant, of various sections of the boring bar tool, tend to occur. Further, with the above arrangement, the mass of each of the various sections of the neck is reduced in the direction of the shank in accordance with a change or and variation in the cross-sectional area of the neck, and vibration occurring at the nose in accordance with the fluctuation in the cutting resistance is not uniformly transmitted, so that vibrations different in frequency from each other in accordance with the mass of each section occur in the portion extending from the nose toward the proximal end of the neck. Moreover, since the flank is provided on the outer periphery of the neck adjacent to the tip and gradually approaches the axis of the shank as it approaches the proximal end of the neck from the forward end thereof, the axis position of the neck is gradually spaced away from the axis of the shank as the proximal end is approached from the forward end. For this reason, the transmitting direction of the vibration changes or varies gradually without being made uniform in the axial direction of the shank. Thus, even if vibration occurs at the nose in accordance with the fluctuation in the cutting resistance, vibrations differing in frequency and phase from each other occur at each section of the neck, and interfere with each other. As a result, the generation of the shivering or shaking vibration is prevented. Furthermore, by the provision of the flank, as the neck is deeply inserted in the bore in the work, that is, as processing proceeds, the gap between the side of the outer peripheral surface of the neck, which is contiguous to the tip, and the wall surface of the bore in the work is gradually enlarged. For this reason, the chips discharged from the tip toward the outer periphery of the neck are easily discharged from the bore through the gap. As a result, the chip discharge ability in the case where the processing depth is particularly large or deep is improved, so that accidents such as the damage of the processed surface, breakage of the tip and so on due to clogging of the chips are avoided. Thus, an excellent advantage is exhibited in that, in combination with the above-mentioned effects of avoiding the shivering or shaking vibration, an excellent finished surface is always obtained. Preferably, the neck is formed with shaft-like configuration in which the cross-sectional configuration of the neck in the plane perpendicular to the axis of the shank forms an arc which is coaxial with a cross-sectional arc in the plane. The cross-sectional area of the neck in the plane is gradually reduced, while not being reduced to a value below that of the cross-sectional area of the shank in the plane as the proximal end of the neck is approached from the forward end thereof. With the above arrangement, since the cross-sectional area of the neck, that is, the diameter thereof, is gradually reduced as the proximal end of the neck is approached from the forward end thereof, the radial gap between the wall surface of the bore in the work and the outer peripheral surface of the neck during cutting is gradually enlarged over the entire peripheral length as the processing proceeds, that is, as the neck is deeply inserted into the bore. For this reason, the chips discharged from the tip toward the outer periphery of the neck are easily discharged from the bore through the gap. As a result, the chip discharge ability in the case where the processing depth is particularly large or deep is improved, so that accidents such as the damage of a processed surface, breakage of the tip and so on due to clogging of the chips are avoided. The boring bar tool further comprises a chip pocket formed in the forward end of the tool body, generally in the form of a circular cylinder. The chip pocket opens to a flank at the forward end of the tool body and an outer peripheral surface thereof. The tip projects toward the forward end and the outer peripheral surface of the tool body. The chip pocket is formed with a groove configuration in a top plan view of the tip. The groove configuration extends from a position adjacent to the cutting edge from the end of the flank located on the radially opposite side with respect to the tip, to the side of the outer peripheral surface of the tool body contiguous to the tip. With the above arrangement, since the chip pocket extends to the side of the outer peripheral surface of the tool body, which is contiguous to the tip, from a midway section of the flank at the forward end of the chip pocket, the forward end of the tool body is not cut out over the entire radial length as is in the conventional chip pocket, but rather a portion behind the chip pocket, that is, a portion at the forward end of the tool body, which is located on the radially opposite side of the forward end of the tool body with respect to the tip, is left in the form of a rib. For this reason, the rigidity of the forward end of the tool body is improved, so that the amount of deformation of the forward end of the tool body due to cutting resistance is reduced. Thus, an excellent advantage is obtained in that the height of the tip is prevented from varying in accordance with the deformation of the forward end of the tool body, so that excellent processing accuracy can be realized. The chip pocket is contiguous to a face of the tip. The chip pocket is composed of a first chip-pocket section and a second chip-pocket section. The first chip-pocket section is inclined at an angle within a range of from 15°to 45° with respect to the axis of the tool body in a top plan view of the tip. The first chip- pocket section opens to an outer peripheral surface of the tool body. The second chip-pocket section extends along a front cutting edge of the tip and opens to the outer peripheral surface of the tool body on the side opposite to the side where the first chip-pocket section opens. With the above arrangement of the invention, the chips generated by the tip are guided to the outside by either one of the first and second chip-pocket sections from the face of the tip. By the fact that a non-cut-out section is left between the first and second chip-pocket sections at the forward end of the tool body, the tool body extends to a location adjacent to the tip. In other words, a thick wall section extending to the vicinity of the tip is formed at the forward end of the tool body. Thus, the wall thickness of the forward end can be secured. That is, the reduction in the rigidity of the forward end of the tool body is restricted, so that shivering or shaking at cutting is restrained, and cutting which is high in accuracy and excellent in finishing is made possible. Preferably, an intersected ridgeline between the bottom surface of the first chip-pocket section and the outer peripheral surface of the tool body extends substantially parallel to the axis of the tool body. With the above arrangement, even if the rake angle of the tool body is made large, reduction in the wall thickness of the portion below the first chip-pocket section is restricted. Thus, it is possible to secure the rigidity of the forward end. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a top plan view of a boring bar tool according to a first embodiment of the parent invention. Fig. 2 is a view as viewed from the arrow II in Fig. 1; Fig. 3 is a fragmentary view as viewed from the arrow III in Fig. 1; Fig. 4 is a fragmentary top plan view of a boring bar tool according to a first modification of the first embodiment illustrated in Figs. 1 through 3; Fig. 5 is a fragmentary side elevational view of the boring bar tool illustrated in Fig. 4; Fig. 6 is a cross-sectional view taken along the line VI - VI in Fig. 4; Fig. 7 is a cross-sectional view taken along the line VII - VII in Fig. 4; Fig. 8 is a fragmentary top plan view of a boring bar tool according to a second modification of the first embodiment illustrated in Figs. 1 through 3; Fig. 9 is a fragmentary side elevational view of the boring bar tool illustrated in Fig. 8; Fig. 10 is a cross-sectional view taken along the line X - X in Fig. 8; Fig. 11 is a cross-sectional view taken along the line XI - XI in Fig. 8; Fig. 12 is a fragmentary top plan view of a boring bar tool according to a third modification of the first embodiment illustrated in Figs. 1 through 3; Fig. 13 is a fragmentary side elevational view of the boring bar tool illustrated in Fig. 12; Fig. 14 is a cross-sectional view taken along the line XIV - XIV in Fig. 12; Fig. 15 is a cross-sectional view taken along the line XV - XV in Fig. 12; Fig. 16 is a fragmentary top plan view of a boring bar tool according to a fourth modification of the first embodiment illustrated in Figs. 1 through 3; Fig. 17 is a fragmentary side elevational view of the boring bar tool illustrated in Fig. 16; Fig. 18 is a cross-sectional view taken along the line XVIII - XVIII in Fig. 16; Fig. 19 is a cross-sectional view taken along the line XIX - XIX in Fig. 16; Fig. 20 is a fragmentary view showing the cutting conditions in an experimental example; Fig. 21 is a top plan view of a boring bar tool according to a second embodiment of the parent invention. Fig. 22 is a view as viewed from the arrow XXII in Fig. 21; Fig. 23 is a fragmentary view as viewed from the arrow XXIII in Fig. 21; Figs. 24(a) and 24(b) are fragmentary views for explanation of a procedure for forming a flank; Fig. 25 is a cross-sectional view taken along the line XXV - XXV in Fig. 21; Figs. 26(a) and 26(b) are fragmentary views showing a modification of the procedure of forming the flank illustrated in Figs. 24(a) and 24(b); Fig. 27 is a fragmentary top plan view of a boring bar tool according to a modification of the second embodiment illustrated in Figs. 21 through 23; Fig. 28 is a fragmentary side elevational view of the boring bar tool illustrated in Fig. 27; Fig. 29 is a cross-sectional view taken along the line XXIX - XXIX in Fig. 27; Fig. 30 is a top plan view of a boring bar tool according to a third embodiment of the parent invention. Fig. 31 is a view as viewed from the arrow XXXI in Fig. 30; Fig. 32 is a fragmentary view as viewed from the arrow XXXII in Fig. 30; Fig. 33 is a fragmentary top plan view of a boring bar tool according to a modification of the third embodiment illustrated in Figs. 30 through 32; Fig. 34 is a fragmentary side elevational view of the boring bar tool illustrated in Fig. 33; Fig. 35 is a cross-sectional view taken along the line XXXV - XXXV in Fig. 33; Fig. 36 is a fragmentary top plan view of a boring bar tool according to a fourth embodiment of the parent invention; Fig. 37 is a view as viewed from the arrow XXXVII in Fig. 36; Fig. 38 is a fragmentary view as viewed from the arrow XXXVIII in Fig. 36; Fig. 39 is a cross-sectional view taken along the line XXXIX - XXXIX in Fig. 36; Fig. 40 is a view similar to Fig. 36, but showing a modification of the fourth embodiment illustrated in Fig. 36; Fig. 41 is a fragmentary top plan view of a boring bar tool according to a first embodiment of the present invention; Fig. 42 is a front elevational view of the boring bar tool illustrated in Fig. 41; Fig. 43 is a fragmentary side elevational view of a principal portion in Fig. 41; Fig. 44 is a cross-sectional view taken along the line XXXXIV - XXXXIV in Fig. 41; Fig. 45 is a schematic cross-sectional view showing the discharge conditions of chips in the embodiment illustrated in Figs. 41 through 43; Fig. 46 is a top plan view of a conventional boring bar tool; Fig. 47 is a front elevational view of the boring bar tool illustrated in Fig. 46; Fig. 48 is a fragmentary side elevational view of the boring bar tool illustrated in Fig. 46; Fig. 49 is a top plan view of another conventional boring bar tool; Fig. 50 is a front elevational view of the boring bar tool illustrated in Fig. 49; Fig. 51 is a fragmentary side elevational view of the boring bar tool illustrated in Fig. 49; Fig. 52 is a top plan view of still another conventional boring bar tool; Fig. 53 is a front elevational view of the boring bar tool illustrated in Fig. 52; and Fig. 54 is a fragmentary side elevational view of the boring bar tool illustrated in Fig. 52. DESCRIPTION OF THE EMBODIMENTS Various embodiments of the parent and present invention are shown in the drawings. It should be noted that like or similar components and parts are designated by the same or like reference numerals throughout the drawings, and the description of the like or similar components and parts will be simplified or omitted to avoid repetition. In particular, the reader is referred to parent EP-A-0405443 for a description of Figures 1 to 40 and 46 to 54. A first embodiment of the present invention will be described with reference to Figs. 41 through 45. This embodiment is also a fifth embodiment of the parent invention. It comprises a turning tool body 501. The tool body 501 is composed of a nose 511, a neck 512 formed at a proximal end of the nose 511, and a shank 513 formed at a proximal end of the neck 512, similarly to the embodiments of the parent invention described in EP-A-0405443. A tip 510 is mounted to the forward end of the tool body 501. A chip pocket 520, which is contiguous to a face 510a of the tip 510, is formed in the forward end of the tool body 501. The chip pocket 520 is composed of a first chip-pocket section 522 and a second chip-pocket section 523. The first chip-pocket section 522 is inclined at an angle  50 that is within a range of from 15° to 45° with respect to the axis C 50 of the tool body 501, and opens to the outer peripheral surface of the tool body 501. The second chip-pocket section 523 extends along the front cutting edge 514 of the tip 510 and opens to a portion of the outer peripheral surface of the tool body 501 which is opposite to the side where the first chip-pocket section 522 opens. The intersected ridgeline E 50 between the bottom surface 522a of the first chip-pocket section 522 and the outer peripheral surface of the tool body 501 extends in a manner in which it is in substantially parallel relation to the axis C 50 of the tool body 501. The tip 510 is formed with a generally rectangular configuration. The tip 510 is seated on a mounting recess 551 which is formed at the forward end of the tool body 501 under conditions such that the mounting recess 551 opens forwardly and laterally of the tool body 501. The tip 510 is fixedly mounted to the tool body 501 by a fixing bolt 552 which extends through the tip 510. As shown in Fig. 41, under conditions in which the tip 510 is mounted to the recess 551, the tip 510 is positioned such that a pair of sides of the tip 510 are abutted respectively against a pair of inner walls of the mounting recess 551 which intersect with each other. As shown in Fig. 43, the upper rake angle α 50 is given to the tip 510. Further, in a side elevational view, the nose 510c of the tip 510 is in agreement with the axis C 50 of the tool body 501. As shown in Fig. 44, the first chip-pocket section 522 is composed of the bottom surface 522a, a side surface 522b and a curved surface 522c, and opens upwardly toward the forward end of the tool body 501. The bottom surface 522a is parallel with the axis C 50 of the tool body 501. The side surface 522b is formed at an opening angle β 50 to the bottom surface 522a. The curved surface 522c smoothly connects the bottom surface 522a and the side surface 522b to each other. It is preferable that an opening angle β 50 is used which is within a range of from 90° to 120°. If the opening angle β 50 is less than 90°, the volume of the chip pocket 520 may become insufficient, so that the chip discharge ability is reduced. Further, if the opening angle β 50 exceeds 120°, the wall thickness of the forward end of the tool body 501 becomes insufficient, so that sufficient rigidity cannot be obtained. As shown in Fig. 43, in a side elevational view, the bottom surface 522a of the first chip-pocket section 522, which is parallel to the axis C 50 of the tool body 501, is positioned below the axis C 50 at a distance L 55 . The first chip-pocket section 522 is such that the angle 50 defined between the axis C 50 and a line of intersection M 50 described along points at which the bottom surface 522a intersects the curved surface 522c is set within a range of from 15° to 45° as described previously and for the reasons discussed previously with reference to the above-described embodiments. A distance L 54 in the radial direction of the tool body 501, from a point at which the bottom surface 522a intersects the ridgeline on the flank at the forward end of the side surface 522b to the nose 510c of the tip 510 is set so as to be equal to or smaller than 1.3S 50 , if the distance in the radial direction of the tool body 501 is defined as being S 50 from the axis C 50 to the nose 510c, for the reasons discussed previously with reference to the aforementioned embodiments. Further, a distance L 53 from the nose 510c of the tip 510 to a point G 52 at which the bottom surface 522a intersects the ridgeline of the side surface 522b adjacent to the outer peripheral surface of the tool body 501, is set within a range of L 54 ≦ L 53 ≦ 3L 54 , for the reasons discussed previously with reference to the aforesaid embodiments. The second chip-pocket section 523 is also such that its cross-section is formed into a configuration substantially similar to the first chip-pocket section 522. Thus, by means of the pair of first and second chip-pocket sections 522 and 523, as shown in Figs. 41 through 43, a thick wall section 554 is formed at the forward end of the tool body 501, and extends to a location adjacent to the side of the tip 510. In the embodiment illustrated in Figs. 41 through 43, a sub-chip pocket 555 substantially flush with the face 510a of the tip 510 is formed, over a minute width, at the junction between the tip 510 and each of the first and second chip-pocket sections 522 and 523. The sub-chip pocket 555 smoothly connects the face 510a and each of the first and second chip-pocket sections 522 and 523 to each other. In the boring bar tool constructed as above, according to the present embodiment, the thick wall section 554 is formed by the first chip-pocket section 522 and the second chip-pocket section 523 at a location adjacent to the side of the tip 510. By doing so, the reduction in the rigidity of the mounting section of the tip 510 is restrained. Even if the upper rake angle α 50 of the tip 510 is made large, the bottom surface 522a is shifted or deviated in parallel relation to the axis C 50 in accordance with the enlargement of the rake angle α 50 , because the bottom surface 522a is parallel to the axis C 50 of the tool body 501. Thus the reduction in the wall thickness of the forward end of the tool body 501 is restrained. The chips generated during cutting are smoothly discharged to the outside through the first chip-pocket section 522 or the second chip-pocket section 523, in accordance with the cutting direction or the cutting conditions, as shown in Fig. 45. Accordingly, shivering or shaking during cutting is restrained, and a boring bar tool which is high in processing accuracy is obtained. In connection with the above, various configurations, dimensions and so on of the various sections illustrated in the present embodiment are merely examples, and may thus be varied or modified on the basis of design requirements or the like.

Claims: A boring bar tool comprising a tip (510), said boring bar tool having a tool body (501) which comprises: a nose (511), said tip (510) being mounted to one side of a forward end of said nose (511); a neck (512) formed at a proximal end of said nose (511); and a shank (513) in the form of a shaft formed at proximal end of said neck (512), wherein said neck (512) has a cross-sectional area in a plane perpendicular to an axis of said shank (513), which is larger than the cross-sectional area of said shank (513) in said plane; and characterised in that: a chip-pocket (520) is formed in a forward end of said tool body, wherein said chip-pocket is contiguous to a face of said tip, said chip-pocket being composed of a first chip-pocket section (522) which is inclined within a range of from 15° to 45° with respect to an axis of said tool body in a top plan view of said tip, said first chip-pocket section opening to an outer peripheral surface of said tool body, and a second chip-pocket section (523) which extends along a front cutting edge of said tip and which opens to the outer peripheral surface of said tool body on the side opposite to the side where said first chip-pocket section opens. A tool according to claim 1, wherein said chip-pocket has a clearance recess (116). A tool according to claim 2, which further includes a cut-out formed in an outer peripheral surface of said neck (130) which is contiguous to said tip, and wherein said cut-out extends substantially over the entire axial length of said neck, and opens to said clearance recess of said chip-pocket. A tool according to claim 1, 2 or 3, which further includes a groove (140) which is formed on an outer peripheral surface of said neck, wherein said groove has its forward end which opens to the clearance recess, and wherein said groove extends toward the proximal end of said neck from a forward end thereof in a straight manner. A tool according to claim 4, wherein said groove comprises a first wall (141) and a second wall (142), wherein said first wall is planar and is substantially flush with said clearance recess, wherein, in a plan view from a direction perpendicular to said first wall, said second wall is gradually inclined in a direction spaced away from the axis of said shank as it approaches the proximal end of said neck from the forward end thereof, wherein said second wall becomes to a planar surface which extends parallel to the axis of said shank, and wherein said groove has a constant width. A tool according to claim 2, which further includes a twisted groove (120) formed in an outer peripheral surface of said neck, and wherein said twisted groove opens to said clearance recess of said chip pocket, and is gradually twisted in a clockwise direction as viewed from the forward end of said nose as it approaches the proximal end of said neck from a forward end thereof. A boring bar tool comprising a tip (510), said boring bar tool having a tool body (501) which comprises: a nose (511), said tip being mounted to one side of forward end of said nose; a neck (512) formed at a proximal end of said nose; and a shank (513) in the form of a shaft formed at proximal end of said neck, wherein said neck is formed into a shaft-like configuration and has a cross-sectional area in a plane perpendicular to an axis of said shank, which is gradually reduced within such a range so as not to become less than the cross-sectional area of said shank in said plane as the proximal end of said neck is approached from a forward end thereof; and characterised in that: a chip-pocket (520) is formed in a forward end of said tool body, wherein said chip-pocket is contiguous to a face of said tip, said chip-pocket begin composed of a first chip-pocket section (522) which is inclined within a rnage of from 15° to 45° with respect to an axis of said tool body in a top plan view of said tip, said first chip-pocket section opening to an outer periperhal surface of said tool body, and a second chip-pocket section (523) which extends along a front cutting edge of said tip and which opens to the outer peripheral surface of said tool body on the side opposite to the side wherein said first chip-pocket section opens. A tool according to claim 7, wherein a flank (218) is formed on an outer periphery of said neck contiguous to said tip, said flank approaching said axis of said shank as it approaches the proximal end of said neck from the forward end thereof. A tool according to any one of the preceding claims, wherein an intersected ridgeline between a bottom surface of said first chip-pocket section and the outer peripheral surface of said tool body extends substantially parallel to the axis of said tool body. A tool according to any one of the preceding claims wherein said neck (512) in cross-section has an outer peripheral arc whose diameter is set to a value within a range of 1.6 to 1.9 times a value given by S, where S is defined as the distance from the axis of said shank (513) to a forward end of said tip (510) in a front elevational view of said nose (511) in an axial direction of said shank (513). A tool according to any one of the preceding claims wherein the neck (512) has a cross-section, in a plane perpendicular to the axis of shank, which is circular.

Inventors: NAKAYAMA MASAAKI, OKAWA MASAYUKI, TSUJIMURA OSAMU, NAKAYAMA, MASAAKI, OKAWA, MASAYUKI, TSUJIMURA, OSAMU, NAKAYAMA, MASAAKI, C/O TOKYO-SEISAKUSHO, OKAWA, MASAYUKI, C/O TOKYO-SEISAKUSHO, TSUJIMURA, OSAMU, C/O TOKYO-SEISAKUSHO
Applicants: MITSUBISHI MATERIALS CORP, MITSUBISHI MATERIALS CORPORATION
Application year: 1990
Main classification: B23B29
IPC codes: B23B27