JP2018114565A - Cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting tool in which occurrence of loosening of a screw fixed to an arbor (main spindle body) is suppressed.SOLUTION: A cutting tool, which is fitted to an end on a tip side of a rotating main spindle body in such a manner that a rotating shaft and an axis of the main spindle body are so made as to coincident with each other, comprises: a tool body which has cutting edge, and on which a first screw hole, which penetrates along the axis, is provided; a first screw rod having a first male screw part which is engaged with the first screw hole, and a second male screw part which is engaged with a second screw hole provided on the main spindle body; and a second screw rod having a third male screw part which is engaged with the first screw hole, and which contacts the end on a tip side in an axial direction of the first screw rod in the first screw hole. The first male screw part and the second male screw part have pitches different from each other, or thread spiral directions different from each other.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a cutting tool.

  In general, a rotary cutting tool used for a milling machine or the like is fixed to an arbor (spindle body) by bolts. The small-diameter cutting tool is fixed to the arbor with a differential screw or a reverse screw in order to prevent the bolt head from interfering with the cutting blade (for example, Patent Document 1).

Japanese Patent No. 2503842

  However, the conventional cutting tool may be loosened in the differential screw due to vibration, thermal expansion, thermal contraction, and the like during cutting.

  The present invention has been made under such a background, and an object of the present invention is to provide a cutting tool in which occurrence of loosening of a screw fixed to an arbor (main shaft body) is suppressed.

  In order to solve the above-described problem, a cutting tool according to one aspect of the present invention is a cutting tool that is attached to an end portion on a distal end side of a rotating main shaft body so that the rotation axis of the main shaft body is aligned with the axis. A tool body provided with a first screw hole having a cutting edge and penetrating along the axis; a first male thread portion engaging with the first screw hole; and a main shaft body. A first screw rod having a second male screw portion that engages with the second screw hole, and a third male screw portion that engages with the first screw hole, and inside the first screw hole. A second screw rod that contacts an end of the first screw rod in the axial direction, and the first male screw portion and the second male screw portion have different pitches from each other, or , The screw spiral direction is different.

According to the above-described configuration, the first screw rod is provided with the first and second male screw portions, and engages with the main shaft body and the tool body, respectively. In addition, the first and second male thread portions have different pitches or different screw thread spiral directions. Therefore, by rotating the first screw rod, the main shaft body and the tool body can be brought close to each other and fixed to each other.
According to the above-described configuration, the first male screw portion of the first screw rod and the third male screw portion of the second screw rod are engaged with the first screw hole of the tool body. The The screw thread of the first male screw part comes into contact with the screw thread of the first screw hole in the inclined part facing upward. On the other hand, the screw thread of the third male screw part contacts the screw thread of the first screw hole in the inclined part facing downward. That is, in the first screw hole, stresses that are separated from each other are generated in the portion that engages with the first male screw portion and the portion that engages with the third male screw portion. In the first male threaded portion, an upward stress is generated that is always pressed against the first screw hole by the action of the third male threaded portion. Therefore, even when vibration is applied to the cutting tool or thermal expansion or thermal contraction occurs in the cutting tool, loosening hardly occurs between the first male screw portion and the first screw hole.

  In the above-described cutting tool, the second screw rod is positioned closer to the proximal end side in the axial direction than the third male screw portion and comes into contact with the end portion on the distal end side in the axial direction of the first screw rod. It is good also as a structure which has a shaft part smaller in diameter than the inner diameter of one screw hole.

  According to the above-described configuration, the shaft portion is disposed between the first male screw portion and the third male screw portion. Due to the elasticity of the shaft portion, a stable surface pressure is applied to the contact portion between the threads of the first male screw portion and the first screw hole and the contact portion between the third male screw portion and the screw threads of the first screw hole. As a result, the effect of suppressing loosening can be enhanced.

  In the cutting tool described above, a spring body disposed in a compressed state is provided between the first screw rod and the second screw rod, and the second screw rod is interposed between the first screw rod and the second screw rod via the spring body. It is good also as a structure which contacts the edge part of the front end side of the axial direction of 1 screw rod.

  According to the above-described configuration, due to the elasticity of the spring body, the contact portion between the threads of the first male screw portion and the first screw hole and the contact portion between the screw threads of the third male screw portion and the first screw hole. A stable surface pressure can be applied to the surface, and as a result, the effect of suppressing loosening can be enhanced.

In the above cutting tool, the first male screw portion and the second male screw portion have different pitches, and the third male screw portion has a smaller pitch than the first male screw portion,
The first screw hole may include a first female screw portion that engages with the first male screw portion and a second female screw portion that engages with the third male screw portion.

  According to the above configuration, since the first and second screw rods contact each other, when a force that rotates the first screw rod in a direction in which the engagement of the first male screw portion is loosened, The second threaded rod tries to run. Moreover, according to the above-described configuration, the pitch of the third male screw portion is smaller than the pitch of the first male screw portion. Even if the first screw rod is rotated in the direction in which the engagement of the first male screw portion is loosened, the first male screw portion is biased upward due to the difference in pitch, and the first male screw portion is fastened. You can increase your power.

  According to the cutting tool of the present invention, it is possible to provide a cutting tool in which the occurrence of loosening of screws fixed to the main shaft body is suppressed.

The perspective view of the cutting tool of 1st Embodiment. Sectional drawing of the cutting tool of 1st Embodiment. The enlarged view of the area | region III of FIG. The enlarged view of the area | region IV of FIG. The enlarged view of the area | region V of FIG. Sectional drawing of the cutting tool of 2nd Embodiment. Sectional drawing of the cutting tool of 3rd Embodiment.

  Hereinafter, a cutting tool according to an embodiment of the present invention will be described with reference to the drawings. In the following drawings, in order to make each configuration easy to understand, the actual structure may be different from the scale, number, or the like in each structure. In the drawings, an XYZ coordinate system is appropriately shown as a three-dimensional orthogonal coordinate system.

<First Embodiment>
FIG. 1 is a perspective view of a cutting tool 1 according to the first embodiment. FIG. 2 is a sectional view of the cutting tool 1 along the axis O. FIG.
In the following description, the positive side in the Z-axis direction (+ Z side, one side) is referred to as “upper side” or “base end side”, and the negative side in the Z-axis direction (−Z side, other side) Is called “lower side” or “tip side”. In addition, the up-down direction in this specification is an example of the attitude | position at the time of use of the cutting tool 1, and does not limit the attitude | position of the cutting tool 1. FIG. Unless otherwise specified, a direction parallel to the axis O is simply referred to as “axial direction” or “vertical direction”, a radial direction centered on the axis O is simply referred to as “radial direction”, and the axis O is the center. The circumferential direction, that is, the circumference of the axis O is simply referred to as “circumferential direction”.

  The cutting tool 1 is a front milling cutter. The cutting tool 1 performs face milling on a workpiece made of a metal material or the like with a cutting blade 31. The cutting tool 1 is attached to a lower end (end portion on the front end side, end portion on one side in the axial direction) 50a of an arbor (main shaft body) 50. The cutting tool 1 is attached to the arbor 50 so that its axis O coincides with the rotation axis J of the arbor 50.

  As shown in FIG. 2, the arbor 50 extends from the proximal end side to the distal end side (that is, the vertical direction) along the rotation axis J. The arbor 50 rotates around a rotation axis J extending in the vertical direction. At the center of the lower end 50a of the arbor 50, a columnar convex portion 51 that protrudes downward is provided. The convex portion 51 fits into a concave portion 49 provided on the upper end surface 40 a of the tool main body 40 and positions the tool main body 40 with respect to the arbor 50. A second screw hole 52 is provided in the center of the convex portion 51. A female screw is formed on the inner peripheral surface of the second screw hole 52.

  As shown in FIG. 2, the cutting tool 1 includes a tool body 40 having a cutting edge 31, a first screw rod 10 for fixing the tool body 40 to the arbor 50, and loosening of the first screw rod 10. A second screw rod 20 to be suppressed.

(Tool body)
As shown in FIG. 1, the tool body 40 includes an insert holder 45 and a plurality of cutting inserts 30. The insert holding body 45 has a substantially cylindrical shape extending in the axis O direction. A plurality of chip pockets 46 formed in a concave shape are provided on the outer periphery of the lower end of the insert holder 45. The plurality of chip pockets 46 are arranged around the axis O so as to be spaced from each other. A mounting seat 47 for mounting the cutting insert 30 is provided on the wall surface of the chip pocket 46 facing the tool rotation direction T.

  The cutting insert 30 is made of a hard material such as a cemented carbide. The cutting insert 30 is detachably fixed to a mounting seat 47 of the insert holder 45 by a clamp screw 35. The cutting insert 30 has a polygonal plate shape. Cutting edges 31 are provided on the polygonal main surface and side surfaces of the cutting insert 30 and the intersecting ridge lines.

  The upper end surface 40a of the tool body 40 is provided with a linear key groove (rotation suppressing portion) 44 extending along the radial direction. The keyway 44 opens upward. A key 56 provided at the lower end 50 a of the arbor 50 is fitted in the key groove 44. By fitting the key 56 in the key groove 44, the rotation of the tool body 40 relative to the arbor 50 is suppressed. That is, the key groove 44 functions as a rotation suppressing unit that suppresses the rotation of the tool body 40 relative to the arbor 50.

  The tool body 40 is provided with a first screw hole 41 penetrating in the vertical direction along the axis O with the axis O as the center. A female screw is formed on the inner peripheral surface of the first screw hole 41. The first screw rod 10 and the second screw rod 20 are inserted into the first screw hole 41.

(First screw rod)
The first screw rod 10 is a rod body extending in the axial direction. The first screw rod 10 includes a first male screw portion 11 and a second male screw portion 12 arranged in the axial direction, and an intermediate shaft portion 13 positioned between the first and second male screw portions 11 and 12. Have. The second male screw portion 12 is located above the first male screw portion 11. Male screws are formed on the outer periphery of the first and second male screw portions 12. On the other hand, no male screw is formed on the outer peripheral surface of the intermediate shaft portion 13.

The first male screw portion 11 is inserted into and engaged with the first screw hole 41 of the tool body 40 from above. On the other hand, the second male screw portion 12 is inserted and engaged with the second screw hole 52 of the arbor 50 from below. In the present embodiment, the first male screw portion 11 and the second male screw portion 12 have different pitches and function as differential screws. More specifically, the pitch of the second male screw portion 12 is larger than the pitch of the first male screw portion 11. Therefore, by rotating the first screw rod 10 around the axis O, the tool body 40 can be brought close to and in contact with the arbor 50 and can be fixed to each other by a reaction force.
In addition, in this embodiment, although the case where the pitch of the 2nd male thread part 12 was larger than the pitch of the 1st male thread part 11, the pitch of the 2nd male thread part 12 of the 1st male thread part 11 was illustrated. Even when the pitch is smaller than the pitch, a structure for fixing the tool body 40 to the arbor 50 can be realized.
As a matter of course, the pitch of the first screw holes 41 with which the first male screw portion 11 is engaged and the pitch of the second screw holes 52 with which the second male screw portion 12 is engaged are set to be different from each other. The pitch is set according to the pitch.

  As another example, the 1st male thread part 11 and the 2nd male thread part 12 may employ | adopt the structure from which the spiral direction of a screw thread differs mutually. As an example, the first male screw portion 11 can be a left-hand screw, and the second male screw portion 12 can be a right-hand screw. In this case, by rotating the first screw rod 10 clockwise, the tool main body 40 can be brought close to and brought into contact with the arbor 50 and can be fixed to each other by a reaction force.

  A hexagonal hole 15 is provided at the lower end (end portion on the front end side) 10 a of the first screw rod 10. A hexagon wrench for rotating the first screw rod 10 is inserted into the hexagon hole 15.

(Second screw rod)
The second screw rod 20 is a rod that extends in the axial direction. The second screw rod 20 includes a third male screw portion 23 and a shaft portion 24 arranged in the axial direction. The shaft portion 24 is located on the upper side (base end side) from the third male screw portion 23. The second screw rod 20 contacts the lower end of the first screw rod 10 at the shaft portion 24. A male screw is formed on the outer periphery of the third male screw portion 23. On the other hand, no male screw is formed on the outer peripheral surface of the shaft portion 24.

  The second screw rod 20 is located on the lower side (front end side) of the first screw rod 10 in the first screw hole 41. That is, the third male screw portion 23 is inserted into the first screw hole 41 from below. The third male screw portion 23 engages with the first screw hole 41.

  The shaft portion 24 has a cylindrical shape. The shaft portion 24 has a smaller diameter than the inner diameter of the first screw hole 41. The upper end of the shaft portion 24 is in contact with the lower end 10 a of the first screw rod 10. The shaft portion 24 is compressed and elastically deformed between the first male screw portion 11 and the third male screw portion 23.

  A hexagonal hole 25 is provided at the lower end (end portion on the front end side) 20 a of the second screw rod 20. A hexagon wrench for rotating the second screw rod 20 is inserted into the hexagon hole 25. The size of the hexagonal hole 25 of the second screw rod 20 is preferably the same as the size of the hexagonal hole 15 of the first screw rod 10.

(Function and effect)
FIG. 3 is an enlarged view of region III in FIG. 2, and shows an engaged state of the second male screw portion 12 and the second screw hole 52. FIG. 4 is an enlarged view of the region IV in FIG. 2 and shows an engaged state of the first male screw portion 11 and the first screw hole 41. FIG. 5 is an enlarged view of a region V in FIG. 2 and shows an engaged state of the third male screw portion 23 and the first screw hole 41.

  As shown in FIGS. 3 to 5, the first to third male screw portions 11, 12, 23 and the first and second screw holes 41, 52 are so-called triangular screws, and each has a triangular cross section. 11a, 12a, 23a, 41a, 52a.

  As shown in FIG. 3, the screw thread 12a of the second male screw part 12 contacts and engages with the screw thread 52a of the second screw hole 52 in the inclined part 12b facing downward. On the other hand, as shown in FIG. 4, the thread 11 a of the first male thread portion 11 contacts and engages with the thread 41 a of the first screw hole 41 in the inclined portion 11 c facing upward. In the first screw rod 10, the pitches of the first and second male screw portions 11 and 12 are different from each other. Therefore, as the first screw rod 10 rotates, the tool body 40 approaches the arbor 50, and the above-described relationship is established. A joint relationship is realized.

  Furthermore, according to the cutting tool 1 of the present embodiment, the second screw rod 20 is inserted into the first screw hole 41 from below the first screw rod 10. The second screw rod 20 contacts the lower end of the first screw rod 10. For this reason, as shown in FIG. 5, the screw thread 23a of the third male screw portion 23 contacts and engages with the screw thread 41a of the first screw hole 41 on the inclined surface 23b facing downward. 1 screw rod 10 is urged upward. As a result, the first screw hole 41 is subjected to stresses that are separated from each other between the portion engaged with the first male screw portion 11 and the portion engaged with the third male screw portion 23. Accordingly, even when vibration is applied to the cutting tool 1 or when thermal expansion or thermal contraction occurs in the cutting tool 1, the looseness between the first male threaded portion 11 and the first screw hole 41 is loosened. Can be suppressed.

  In addition, according to the cutting tool 1 of the present embodiment, the second screw rod 20 has a shaft portion 24 that is located above the third male screw portion 23 and has a smaller diameter than the inner diameter of the first screw hole 41. That is, the shaft portion 24 that is not engaged with the screw is disposed between the first male screw portion 11 and the third male screw portion 23. The shaft portion 24 has elasticity. Therefore, the shaft portion 24 presses the first shaft portion 10 upward and the second shaft portion 20 downward, and the contact portion between the threads of the first male screw portion 11 and the first screw hole 41. In addition, a stable surface pressure is applied to the contact portion between the third male screw portion 23 and the first screw hole 41. Thereby, the effect of loosening suppression can be heightened.

  In the present embodiment, the second screw rod 20 directly contacts the lower end of the first screw rod 10. However, as long as the first screw rod 10 is configured to apply an upward stress from the second screw rod 20, contact via an inclusion may be used.

Second Embodiment
FIG. 6 is a cross-sectional view along the axis O of the cutting tool 101 of the second embodiment. Hereinafter, based on FIG. 6, the cutting tool 101 of 2nd Embodiment is demonstrated. The cutting tool 101 of the second embodiment is mainly different from the first embodiment in that it has a spring body 102.
In addition, about the component of the same aspect as the above-mentioned embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  The cutting tool 101 includes a tool body 40, a first screw rod 10, a second screw rod 20, and a spring body 102. The spring body 102 of the present embodiment is a coil spring, but is not limited thereto as long as it is a spring that is elastically deformed along the axial direction. The spring body 102 is disposed in a compressed state between the first screw rod 10 and the second screw rod 20 inside the first screw hole 41 of the tool body 40. That is, the second screw rod 20 contacts the lower end of the first screw rod 10 via the spring body 102. The spring body 102 biases the first screw rod 10 upward and biases the second screw rod 20 downward.

  According to the cutting tool 101 of the second embodiment, due to the elasticity of the spring body 102, the contact portion between the first male screw portion 11 and the first screw hole 41 and the third male screw portion 23 and the first male screw portion 41. A stable surface pressure can be applied to the contact portion between the screw threads of the screw hole 41. The effect of suppressing loosening can be enhanced.

<Third Embodiment>
FIG. 7 is a cross-sectional view along the axis O of the cutting tool 201 of the third embodiment. The third embodiment liquid cutting tool 201 will be described below with reference to FIG. The cutting tool 201 of the third embodiment is mainly different from the first embodiment in the configuration related to the pitch of the third male screw portion 223 and the first screw hole 241.
The cutting tool 201 includes a tool main body 240, a first screw rod 10, and a second screw rod 220.

  The second screw rod 220 is a rod body extending in the axial direction. The second screw rod 220 has a third male screw part 223 having a male screw formed on the outer periphery. The third male screw portion 223 has a smaller pitch than the first male screw portion 11 of the first screw rod 10.

  The second screw rod 220 is positioned below the first screw rod 10 in the first screw hole 241. Inside the first screw hole 241, the upper end of the second screw rod 220 contacts the lower end of the first screw rod 10.

  The tool body 240 is provided with a first screw hole 241 penetrating in the vertical direction about the axis O. The first screw hole 241 includes a first female screw portion 241a and a second female screw portion 241b arranged in the axial direction, and a counterbore portion 241c positioned between the first and second female screw portions 241a and 241b. .

  The first screw rod 10 is inserted into the first female screw portion 241a from above, and the first male screw portion 11 is engaged therewith. Further, the second screw rod 220 is inserted into the second female screw portion 241b from the lower side, and the third male screw portion 223 is engaged therewith. The first and second female screw portions 241a and 241b are set to a pitch corresponding to the pitch of the male screw portions to be engaged. Therefore, the pitch of the second female screw portion 241b is smaller than the pitch of the first female screw portion 241a.

  The counterbore part 241c is located between the first female screw part 241a and the second female screw part 241b. The counterbore part 241c is sufficiently larger than the root diameter of the first female screw part 241a and the second female screw part 241b.

When a force that rotates the first screw rod 10 in a direction in which the engagement of the first male screw portion 11 is loosened, the first and second screw rods 10 and 220 try to rotate to contact each other. To do. According to this embodiment, the pitch of the third male screw portion 223 is smaller than the pitch of the first male screw portion 11. Even if the first screw rod 10 is rotated in the direction in which the engagement of the first male screw portion 11 is loosened, the first male screw portion 11 is biased upward due to the difference in pitch, and the first male screw portion The fastening force of the part can be increased.
In the present embodiment, it is preferable to adopt a configuration in which the first and second male thread portions 11 and 12 have different pitches. That is, when the first and second male screw portions adopt a configuration in which the screw thread spiral directions are different from each other (reverse screw), the effect of the second screw rod 220 is not sufficiently exhibited. This is because when the first and second male screw portions are reverse screws, when the first screw rod 10 is rotated in the direction in which the engagement of the first male screw portion is loosened, the first screw rod and the second screw This is because it is difficult to rotate the second screw rods apart from each other.

  Although various embodiments of the present invention have been described above, each configuration in each embodiment and combinations thereof are examples, and addition, omission, replacement, and configuration of configurations are within the scope without departing from the spirit of the present invention. Other changes are possible. Further, the present invention is not limited by the embodiment.

  For example, the configuration in which the spiral directions of the threads of the first and second male thread portions 11 and 12 described in the first embodiment are changed is adopted not only in the first embodiment but also in other embodiments. Is possible.

DESCRIPTION OF SYMBOLS 1,101,201 ... Cutting tool 10 ... 1st screw rod 10a ... Lower end (end part of front end side)
DESCRIPTION OF SYMBOLS 11 ... 1st male thread part 12 ... 2nd male thread part 23,223 ... 3rd male thread part 24 ... Shaft part 20,220 ... 2nd screw rod 20a ... Lower end (end part by the side of a front end)
30 ... Cutting insert 31 ... Cutting blade 40, 240 ... Tool body 41, 241 ... First screw hole 52 ... Second screw hole 50 ... Arbor (main shaft body)
102 ... Spring body 241a ... First female screw portion 241b ... Second female screw portion O ... Axis line J ... Rotating shaft

Claims (4)

A cutting tool that is attached to an end of the rotating main shaft body on the front end side so that the rotation axis and the axis of the main shaft body coincide with each other,
A tool body provided with a first screw hole having a cutting edge and penetrating along the axis;
A first screw rod having a first male screw portion engaged with the first screw hole, and a second male screw portion engaged with a second screw hole provided in the main shaft body;
A second threaded rod that has a third threaded portion that engages with the first threaded hole and that is in contact with an end of the first threaded rod in the axial direction inside the first threaded hole; And comprising
The first male screw part and the second male screw part have different pitches from each other or different screw spiral directions from each other.
Cutting tools. The second screw rod is positioned closer to the proximal end side in the axial direction than the third male screw portion, contacts the end portion on the distal end side in the axial direction of the first screw rod, and has an inner diameter of the first screw hole. Having a smaller diameter shaft,
The cutting tool according to claim 1. A spring body arranged in a compressed state between the first screw rod and the second screw rod;
The second screw rod is in contact with the end portion on the distal end side in the axial direction of the first screw rod via a spring body.
The cutting tool according to claim 1 or 2. The first male screw portion and the second male screw portion have different pitches from each other,
The third male screw portion has a smaller pitch than the first male screw portion,
The first screw hole includes a first female screw portion with which the first male screw portion is engaged, and a second female screw portion with which the third male screw portion is engaged.
The cutting tool as described in any one of Claims 1-3.

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