JP5805019B2 - Cutting tool gripper - Google Patents

Description

  The present invention relates to a cutting tool gripping tool for attaching a cutting tool to a cutting machine, and more particularly to a cutting tool gripping tool for attaching to a cutting machine after inserting and fixing one end of a rod-shaped cutting tool in an attachment hole.

  In cutting work in which cutting is performed by moving a workpiece and a cutting tool relative to each other while contacting each other, a reduction in machining accuracy due to vibration becomes a problem. In particular, in the boring process that cuts the inner peripheral surface of the workpiece, the cutting tool is supported by cantilevering the vicinity of one end of a long bar-like cutting tool such as a boring bar. "Is likely to occur. In view of this, a damping mechanism made of a damping alloy that suppresses vibration is provided in a cutting tool gripper for attaching the cutting tool to a cutting machine.

  For example, in Patent Document 1, a fitting hole along the axis of a cylindrical gripping tool body made of steel or the like is used to prevent vibration generated in a boring bar during cutting from being directly transmitted to the cutting tool gripping tool. A cylindrical sleeve made of a damping member is inserted into the inner peripheral surface of the sleeve, and a shank portion of a boring bar is inserted into the inner peripheral surface of the sleeve and pressed and fixed with a clamp screw. The outer peripheral surface of the shank part opposite to the clamp screw is used as a pressing surface, and a damping member is interposed between the pressing surface and the inner surface of the fitting hole facing the boring. The vibration generated in the bar is attenuated and absorbed by the damping member to suppress the swing of the boring bar, and in particular, “batter vibration” due to resonance between the shank portion and the gripper main body is prevented. Examples of the damping member that can be used for the pressing surface portion include aluminum, copper, zinc, brass, an alloy containing these as a main component, a damping steel plate, and the like.

  Further, in Patent Document 2, the core member is screwed so as to be fitted along the axial center of the metal sleeve, and the shank of the cutting tool is fitted and attached to the tool holding hole of the core member. It is disclosed that pure magnesium or a magnesium alloy that is lightweight and excellent in vibration absorption can be used for the core member. By making the sleeve and the core member in the cutting tool gripping tool separate, the core member tries to absorb vibration transmitted from the cutting tool to the mounting base of the cutting machine via the cutting tool gripping tool during the cutting process.

  Patent Document 3 discloses that a damping member is interposed between a cutting tool and a tool base that presses and fixes the cutting tool. In such a damping member, the higher the damping coefficient, the more the vibration during cutting is performed. While it is possible to suppress the impact response when the cutting tool bites, etc., the damping performance and the rigidity and strength expressed by the tensile strength are in a trade-off relationship. It states that the vibration of the cutting tool is intensified and the machining accuracy is reduced. In addition, as the damping member, a metal material having a tensile strength of 500 to 650 MPa and a logarithmic attenuation rate of 0.2 to 0.35, for example, Mn is used as a base, and the basic composition is atomic%, Cu: Damping alloys containing 20 ± 5%, Ni: 5 ± 3%, and Fe: 2 ± 1% are preferred.

Japanese Utility Model Publication No. 05-088804 Registration No. 3153247 JP 2004-202649 A

  As disclosed in Patent Documents 1 to 3, it is widely performed that a damping member is interposed between a cutting tool and a portion where the tool is pressed and fixed. However, although the damping characteristics of the damping member vary greatly depending on the material, the design of the cutting tool gripper and the like optimized for each material of the damping member has not been considered. That is, it cannot always be said that the cutting tool vibration is suppressed to the maximum and cutting with high processing accuracy is given.

  The present invention has been made in view of such a situation, and an object thereof is to provide a cutting tool gripper capable of performing cutting with excellent processing accuracy.

  The cutting tool gripping tool according to the present invention is a cutting tool gripping tool for attaching to a cutting machine after inserting and fixing one end portion of a rod-shaped cutting tool into an attachment hole, and is Cu: 16.9- 27.7%, Ni: 2.1 to 8.2%, Fe: 1.0 to 2.9%, C: 0.05% or less, the balance is Mn and inevitable impurities A damping alloy tube having a central through hole along the longitudinal direction as the mounting hole and having a threaded outer peripheral surface is made of a material having a Young's modulus larger than that of the damping alloy. The rigid holding tube body is screwed and fixed along the threaded inner surface of the cylinder.

  According to this invention, the damping alloy tube body made of an Mn-based twin type damping alloy having a high damping capacity capable of efficiently absorbing vibrations in a wide frequency range while having relatively high rigidity and strength is maintained rigid. In a cutting process in which a cutting tool is attached to such a cutting tool gripping tool by screwing and fixing in a wide area along the tube inner surface of the tubular body, excellent processing accuracy can be given.

  In the above-described invention, the damping alloy tube has an end on the opposite side to the rigid holding tube so as to press a flange provided at an end in the longitudinal direction against an end surface of the rigid holding tube. It may be characterized by being screwed and fixed along the inner surface of the cylinder while being inserted. According to this invention, a damping alloy tube made of an Mn-based twin type damping alloy having relatively high rigidity and strength is screwed and fixed more firmly along a cylindrical inner surface of the rigid holding tube. Thus, it is possible to give better processing accuracy in the cutting processing with the cutting tool attached to the cutting tool gripping tool.

It is the sectional side view and front view which show the cutting tool holding tool by this invention. It is the sectional side view and front view which show the component of the cutting tool holding tool by this invention. It is the side view and front view which show the component of the cutting tool holding tool by this invention. It is a sectional side view which shows the fixing method of the cutting tool by the cutting tool holding tool by this invention. It is a figure which shows the measurement result of the roundness in cutting. It is a figure which shows the measurement result of the surface roughness in cutting. It is a sectional side view which shows the fixing method of the cutting tool by the cutting tool holding tool in the other Example by this invention.

  A cutting tool gripper which is one embodiment according to the present invention will be described with reference to FIGS. 1 to 4.

  As shown in FIG. 1, a gripping tool 1 for gripping a cutting tool and attaching the cutting tool to a cutting machine includes a holding tube (rigid holding tube) 2 made of a substantially cylindrical rigid material, and a substantially cylindrical control. A sleeve (damping alloy tube) 3 made of a vibration alloy is coaxially combined. The holding tube 2 has a flange 21 at one end thereof, the sleeve 3 is inserted from the end opposite to the flange 21, and the side surface of the flange portion 31 provided at one end of the sleeve 3 is held by the holding tube 2. It is made to contact | abut to the end surface 24 of this.

  Referring also to FIG. 2, the holding tube body 2 is provided with an internal thread on its inner peripheral surface 22 over the entire length along the axis. Further, the holding tube body 2 is provided with a through hole 23 that penetrates from the outer peripheral surface to the inner peripheral surface 22 and attaches a bolt for fixing the cutting tool as will be described later. A plurality of through holes 23 are provided along the axial direction. The holding tube body 2 is made of, for example, steel such as S45C, and is a rigid body having a Young's modulus that is at least larger than that of a sleeve 3 to be described later, and typically has a Young's modulus that is twice or more larger than that of the sleeve 3. It is preferable to have.

  As shown in FIG. 3, the sleeve 3 is provided with a male screw along the axial direction on the outer peripheral surface 32 other than the flange portion 31, and corresponds to the female screw on the inner peripheral surface 22 of the holding tube body 2 described above. It can be screwed. The inner peripheral surface of the tubular sleeve 3 defines a mounting hole 34 for inserting and mounting a cutting tool. The sleeve 3 is provided with a plurality of through holes 33 penetrating in the radial direction from the outer peripheral surface 32 to the inner peripheral surface so as to correspond to the through holes 23 of the holding tube body 2. That is, each of the through holes 33 is provided at a position that communicates with the through hole 23 when the sleeve 3 is screwed and fixed to the holding tube 2 (see FIG. 1).

  The sleeve 3 is made of a twin-type Mn-based damping alloy, and by mass, Cu: 16.9 to 27.7%, Ni: 2.1 to 8.2%, Fe: 1.0 to 2. From a Mn—Cu—Ni—Fe based vibration damping alloy having a component composition of 9% and C: 0.05% or less with the balance being Mn and inevitable impurities (low-content elements such as O and N) Become. Here, the composition range (all are mass%) of each component in this damping alloy is demonstrated. With respect to Cu, if less than 16.9%, twins are not generated, and if it exceeds 27.7%, segregation increases and sufficient vibration damping characteristics cannot be obtained. A more preferable composition range is 19.7 to 25.0%. About Ni, it can improve a damping characteristic by adding as a 3rd element with Mn and Cu which are main elements. Here, if it is less than 2.1%, the twin formation cannot be changed, and if it exceeds 8.2%, the contribution to the twin formation is saturated. About Fe, it can improve a damping characteristic more by adding as Mn, Cu, and Ni as a 4th element. Here, if it is less than 1.0%, the twin formation cannot be changed, and if it exceeds 2.9%, the contribution to the twin formation is saturated. Further, by setting C to 0.05% or less, even if Mn evaporates and the relative concentration of C rises, deterioration of damping characteristics can be prevented.

  As described above, the vibration damping alloy of this embodiment forms twins and absorbs vibrations by converting vibration energy given from the outside into frictional heat at the twin crystal interface. Compared with a general damping alloy, it has a high damping capacity for vibrations in a wide frequency range and can absorb the vibrations efficiently. In particular, by applying a compressive stress, frictional heat is generated at the twin interface even with a smaller stress, and vibration can be efficiently absorbed. Moreover, it has high rigidity and strength compared with a general damping alloy.

  Referring to FIG. 1 again, the inner peripheral surface 22 of the holding tube body 2 and the outer peripheral surface 32 of the sleeve 3 are screwed together, and are fixed in a larger area compared to the case where they are fitted with smooth surfaces. doing. Further, the sleeve 3 is made of a surface that is threaded and pressed from the end surface 24 of the holding tube body 2 that is a rigid body having a larger Young's modulus, and is threaded and inclined from the axial direction. A large surface pressure is applied to the outer peripheral surface 32, and the sleeve 3 is firmly fixed to the holding tube 2.

  As shown in FIG. 4, the above-described gripping tool 1 is inserted into the holding hole 64 of the holder 60 fixed to the cutting machine (not shown) after the grip portion 52 of the rod-shaped cutting tool 50 is inserted into the mounting hole 34. Is done. At this time, the side surface of the flange 21 contacts the holder 60, and the tip 51 of the cutting tool 50 protrudes from the holder 60. In this state, when a bolt hole 63 having a female screw provided in the holder 60 is disposed at a position communicating with the through holes 23 and 33 of the gripping tool 1, and a plurality of bolts 4 are tightened through the bolt holes 63. The tip of the bolt 4 comes into contact with the cutting tool 50. The cutting tool 50 is pressed in the traveling direction of the bolt 4, and the outer peripheral surface on the opposite side to the portion in contact with the bolt 4 is pressed and fixed to the inner peripheral surface of the sleeve 3. Thereby, cutting can be performed while moving the tip 51 relative to the workpiece.

  According to the above-described embodiment, the sleeve 3 made of a twin-type Mn-based damping alloy is larger than the case where the sleeve 3 is fitted to the inner peripheral surface of the highly rigid holding tube 2 with a smooth inner peripheral surface. The area is screwed and fixed. Then, the plurality of bolts 4 are tightened, and the outer peripheral surface of the cutting tool 50 opposite to the portion where the bolts 4 are in contact is pressed and fixed to the inner peripheral surface of the sleeve 3. That is, the sleeve 3 fixes the cutting tool 50 while being compressed by being biased and compressed by the holding tube 2 over a wide area in the circumferential direction with a larger area over the entire area in the axial direction due to its rigidity. This makes it possible to take advantage of the characteristics of the twin-type Mn-based damping alloy having higher vibration damping ability under compressive stress and to efficiently absorb vibrations in a wide frequency range and to obtain a gripping tool 1 having high damping ability. Give. That is, it gives excellent processing accuracy.

  It is to be noted that the screw of the sleeve 3 is advanced by being screwed into the holding tube 2 while pressing the side surface of the collar portion 31 of the sleeve 3 against the end surface 24 of the holding tube 2 made of a rigid body having a larger Young's modulus. The force in the direction and the force exerted by the flange 31 of the sleeve 3 to counter this are constituted by the outer peripheral surface 32 of the sleeve 3 that is threaded, that is, the threaded surface that is inclined with respect to the axial direction. The sleeve 3 can be fixed to the holding tube 2 more firmly. That is, vibration generated in the cutting tool 50 can be absorbed more efficiently.

[Evaluation test]
Next, the results of cutting (boring) using the cutting tool gripper in the above-described embodiments of the present invention and comparative examples will be described with reference to FIGS. The results of cutting were evaluated by measuring roundness and surface roughness as described later.

  In Example 1, the holding tube body 2 made of S45C has, in mass%, Cu: 22.4%, Ni: 5.2%, Fe: 2.0%, C: 0.01%, the balance being Mn and This is a cutting tool gripping tool in which a sleeve 3 made of a Mn—Cu—Ni—Fe based damping alloy having a component composition as an inevitable impurity is screwed (hereinafter referred to as “screw type”). Specifically, the holding tube body 2 has an outer diameter of 40 mm, and an M33 × 2 female screw is cut over the entire length on the inner peripheral surface. The sleeve 3 has an inner diameter of 25.2 mm, and an M33 × 2 male screw is cut on the outer peripheral surface. The total length of the cutting tool gripping tool to which these are screwed and fixed, that is, the total length of the sleeve 3 is 96 mm.

  Comparative Example 1 is a cutting tool gripping tool in which the sleeve 3 is not screwed to the holding tube 2 in the first embodiment, but a cylindrical sleeve is cooled and fixed to the holding tube (hereinafter, referred to as “cutting tool gripper”). Referred to as “fitting type”). The boundary diameter is 31 mm, and other dimensions are the same as those in the first embodiment. Comparative Example 2 and Comparative Example 3 are cutting tool gripping tools in which a holding tube and a sleeve are integrally formed (hereinafter referred to as “integrated type”). The materials of Comparative Example 2 and Comparative Example 3 are S45C used for the holding tube 2 of Example 1 and the Mn—Cu—Ni—Fe based damping alloy used for the sleeve 3 of Example 1, respectively.

  Cutting is performed on a cylindrical workpiece having a length of 200 mm, an outer diameter of 100 mm, and an inner diameter of 62 mm made of SUS304, with a cutting speed of 100 m / min, a cutting amount of 0.5 mm, and a feeding speed of 0.2 mm / rev. The boring of the tool with a feed distance of 80 mm was performed in 3 passes with a tool protrusion amount of 140 mm.

  The roundness was measured using a commercially available three-dimensional measuring instrument on the inner peripheral surface of the processed hole after three passes of boring. The measurement was performed at four locations at a depth of 3 mm, 6 mm, 25 mm, and 45 mm from the end face of the processed hole, and an average value of the measured values at the four locations was recorded for comprehensive evaluation of each example. The average value of each example is shown in the lower part of FIG.

  Regarding the surface roughness, three points are measured with a commercially available surface roughness meter every time one pass of boring at a position 30 mm deep from the end surface of the inner peripheral surface of the workpiece, and the average value is obtained. It was. Boring was performed for 3 passes, and the average value of the surface roughness Ra for each pass was recorded.

  As shown in FIGS. 5 and 6, in the “screw type” Example 1, the roundness is 6.3 to 8.7 μm, the average is 7.4 μm, and the surface roughness Ra is 1.69 to 1. It was 93 μm. The surface roughness Ra was a stable value even when the number of passes was repeated.

  On the other hand, in Comparative Example 1 of “fitting type”, the roundness was 11.9 to 21.4 μm, and the average was 16.3 μm, which was larger than that of Example 1. Further, the surface roughness Ra was 2.42 to 5.01 μm, which was larger than that in Example 1. That is, Example 1 was superior to Comparative Example 1 in processing accuracy evaluated by roundness and surface roughness Ra.

  In the “integrated” comparative example 2 made of S45C, the roundness was 9.2 to 10.1 μm, and the average was 9.7 μm, which was larger than that of the first example. Further, the surface roughness Ra was 3.99 to 5.35 μm, which was larger than that of Example 1. That is, Example 1 was superior to Comparative Example 2 in processing accuracy evaluated by roundness and surface roughness Ra. In Comparative Example 2, although the amplitude of vibration generated in the cutting tool is relatively small and the roundness is relatively high, it is considered that the surface roughness becomes rough because the generated vibration cannot be absorbed.

  In Comparative Example 3 of “integrated type” made of a Mn—Cu—Ni—Fe based damping alloy having the same composition as that of Example 1, the roundness was 15.0 to 25.3 μm and the average was 18.4 μm It became larger than 1. Further, the surface roughness Ra was 6.54 to 9.19 μm, which was larger than that of Example 1. That is, Example 1 was superior to Comparative Example 3 in processing accuracy evaluated by roundness and surface roughness Ra. Compared to the screw type (Example 1) and fitting type (Comparative Example 1), the damping alloy is thicker, so twin deformation becomes insufficient, and vibration cannot be efficiently converted into frictional heat, which is good I think that it was not possible to obtain a good vibration control.

  As described above, the boring processing using the cutting tool gripping tool of Example 1 was very excellent in processing accuracy evaluated by roundness and surface roughness. The gripping tool 1 uses a twin-type Mn-based damping alloy that has high rigidity and strength as compared with a general damping alloy, and can efficiently absorb vibrations in a wide frequency range, particularly under a compressive stress. The high processing accuracy can be achieved by screwing and fixing the sleeve 3 to the highly rigid holding tube 2.

  Further, as shown in FIG. 7, a continuous female screw is given to the inner peripheral surfaces of the through hole 23 of the holding tube body 2 and the through hole 33 of the sleeve 3, and a set screw 42 is fastened to the tip so that the tip is cut by the cutting tool 50. The cutting tool 50 may be pressed against and fixed to the inner peripheral surface of the sleeve 3. At this time, the set screw 42 does not protrude from the outer peripheral surface of the holding tube 2 and does not contact the holder 60. The holding tube body 2 is pressed and fixed to the holder 60 with a bolt (not shown). It can reduce that the set screw 42 does not contact the holder 60 and the vibration generated in the cutting tool 50 is transmitted to the outside of the cutting tool gripping tool 1. As another example, a shorter set screw 42 may be used so as not to protrude from the outer peripheral surface of the sleeve 3. That is, by preventing the set screw 42 from contacting not only the holder 60 but also the holding tube 2, vibration generated in the cutting tool 50 can be prevented from being transmitted outside without passing through the sleeve 3.

  Although the exemplary embodiments according to the present invention have been described so far, the present invention is not necessarily limited thereto. Those skilled in the art will recognize a variety of alternative embodiments and modifications without departing from the spirit of the invention or the scope of the appended claims.

DESCRIPTION OF SYMBOLS 1 Grasping tool 2 Holding tube 3 Sleeve 22 Inner peripheral surface 31 Gutter part 32 Outer peripheral surface 34 Mounting hole 50 Cutting tool

Claims (2)

A cutting tool gripping tool for attaching to a cutting machine after inserting and fixing one end of a rod-shaped cutting tool in an attachment hole,
In mass%, Cu: 16.9 to 27.7%, Ni: 2.1 to 8.2%, Fe: 1.0 to 2.9%, C: 0.05% or less, the balance A damping alloy tube body comprising a damping alloy having a component composition with Mn and unavoidable impurities, a central through hole along the longitudinal direction as the mounting hole, and having a threaded outer peripheral surface. A cutting tool gripping tool, wherein the rigid holding tube made of a material having a large Young's modulus is screwed and fixed along the threaded inner surface of the cylinder. The vibration-damping alloy tube is inserted into the rigid holding tube while the opposite end thereof is inserted into the rigid holding tube so that the flange provided at the end in the longitudinal direction is pressed against the end surface of the rigid holding tube. The cutting tool gripping tool according to claim 1, wherein the cutting tool gripping tool is screwed and fixed along the inner surface.

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