Tool Holder and Machine Tool

Abstract

To provide a tool holder and a machine tool capable of stably obtaining high vibration suppressing effect even if the same has versatility at low costs.SOLUTION: A tool holder 1 includes a sleeve 11 that grips a tool 24, and a base 2 that has a tool insertion hole 3 into which a sleeve 11 is inserted together with the tool 24, a tool 24 inserted into the tool insertion hole 3, and a tool fixing bolt 5 fixing the sleeve 11. The sleeve 11 includes a fixing means avoidance port 12 with which the tool fixing bolt 5 can directly add fixing force regulating the relative movement of the tool 24 with respect to the tool holder 1 to the tool 24 when vibrations occurs due to machining, and a tool gripping portion 14 that can grip the tool 24 with fixing force lower than the tool fixing bolt 5 and can permit the relative movement of the tool 24 with respect to the tool holder 1 when vibrations occurs due to machining.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a tool holder having a function of suppressing vibrations generated in a tool during machining in a machine tool that performs machining while relatively moving a tool and a workpiece, and a machine tool including the tool holder.

Background Art

[0002] In a machine tool that supports a tool on a rotatable workpiece and relatively moves the tool and the workpiece while feeding them to machine the workpiece, the tool may be used with a large protrusion amount, such as in boring. A tool holder for holding such a tool is known to be fixed by inserting the tool into a tool insertion hole having a split structure and tightening a bolt (see Non-Patent Document 1). FIG. 13 is a schematic configuration diagram showing the configuration of a conventional split tool holder 31. For convenience, the tip side (tip 25 side) of the tool 24 in FIG. 13 will be described as the front, and the upper side of the tool holder 31 will be described as the upper side. FIG. 14 is a schematic configuration diagram showing the configuration of the split tool holder 31 in the cross section D-D of FIG. 13 (a cross section in a plane defined by the front-rear and up-down directions). In this example, it is applied to a lathe 21 having a turret 22. The split tool holder 31 has a tool insertion hole 32 having a diameter smaller than that of the tool 24, and a slit 33 that is connected to the outside of the tool insertion hole 32 and penetrates and opens in the longitudinal direction of the tool 24. Further, it includes a holder fixing bolt 35 for fixing the split tool holder 31 to the mounting surface 23 on the outer periphery of the turret 22, a tool phase fixing bolt 36 for fixing the angular position of the tool 24 in the circumferential direction with respect to the split tool holder 31, and a holder expansion bolt 34 for increasing the diameter of the tool insertion hole 32 so that the tool 24 can be inserted. When setting up the tool, tighten the holder expansion bolt 34 and press it against the lower surface of the slit 33 to increase the diameter of the tool insertion hole 32, and insert the tool 24 from the rear end. Next, adjust the tool 24 to the desired protrusion length and angular position, and fix the angle of the tool 24 using the tool phase fixing bolt 36. Finally, after loosening the holder expansion bolt 34, tighten the holder fixing bolt 35 to fix the split tool holder 31 to the turret 22 and increase the contact pressure on the tool 24 to fix the tool 24.

[0003] When using a tool 24 with a large protrusion amount, due to the decrease in tool rigidity, large machining vibrations (hereinafter referred to as chatter) may occur, causing problems such as tool 24 breakage and poor machining surface quality. In the split tool holder 31, although a certain degree of vibration suppression effect can be expected by improving the holding rigidity with the tool phase fixing bolt 36 and the holder fixing bolt 35, there is a limit to the improvement of the holding rigidity. Therefore, as a prior art for effectively suppressing chatter, Patent Document 1 discloses an invention in which a damping structure (vibration damping piece) is provided on the tool to improve vibration damping performance. In addition, Patent Document 2 discloses an invention in which the rotational speed of the spindle is continuously varied by control.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Patent Documents

[0005]

Patent Document 1

[0006] However, in the method of Patent Document 1, while high damping performance can be obtained, it is necessary to provide a damping structure for each tool, which makes it expensive and has problems with versatility. Further, in the method of Patent Document 2, while a vibration suppression effect can be obtained for all tools, there are problems such as ineffective control during high-speed rotation due to restrictions on motor performance and the like.

[0007] Therefore, the present disclosure has been made in view of the above problems, and an object thereof is to provide a tool holder and a machine tool that are low-cost and versatile, and that can stably obtain a high vibration suppression effect. [Means for Solving the Problems]

[0008] To achieve the above object, a first configuration of the present disclosure is a tool holder provided in a machine tool for holding a tool, including: a sleeve for gripping the tool; a base having a tool insertion hole into which the sleeve is inserted together with the tool, and fixing means for fixing the tool and the sleeve inserted into the tool insertion hole; the sleeve has a fixing means avoidance port that enables the fixing means to directly apply a fixing force to the tool to restrict relative movement of the tool with respect to the tool holder when vibration due to machining occurs, and grips the tool with a fixing force lower than that of the fixing means Shi and a tool gripping portion that allows relative movement of the tool with respect to the tool holder when vibration due to machining occurs, and is characterized by this. Another aspect of the first configuration of the present disclosure is characterized in that, in the above configuration, the tool gripping portion is provided on the tip side of the tool with respect to the fixing means avoidance port. Another aspect of the first configuration of the present disclosure is that, in the above configuration, the tool gripping portion perpendicular to the tool axis in has a cross-sectional shape that is equal to or smaller than the cross-sectional shape of the tool perpendicular to the said tool axis in in the cross-sectional shape the said This is characterized by are similar being smaller than the cross-sectional shape of the tool Another aspect of the first configuration of the present disclosure is that, in the above configuration, the sleeve is formed with a slit that communicates with at least the tool gripping portion inner surface of and opens to the outside of the sleeve along the axial direction of the tool insertion hole. This is characterized by Another aspect of the first configuration of the present disclosure is that, in the above configuration, it is characterized by including an expansion mechanism capable of expanding the tool gripping portion in the radial direction of the sleeve through the slit To achieve the above object, a second configuration of the present disclosure is a machine tool, characterized by including the tool holder according to any one of the first configurations

Advantages of the Invention

[0009] According to the present disclosure, it is possible to stably impart generally high damping properties to any tool at the same manufacturing cost as an existing split holder and with the same number of setup man-hours. Therefore, it is possible to obtain a stable and high vibration suppression effect while being low-cost and general-purpose, and to realize highly efficient machining

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

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Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Embodiments for Carrying out the Invention

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing the configuration of a tool holder 1. For convenience, the tip side (tip 25 side) of the tool 24 in FIG. 1 will be described as the front, and the upper side of the tool holder 1 will be described as the upper side. FIG. 2 is a schematic diagram showing the shape of the sleeve 11 constituting the tool holder 1. FIG. 3 is a schematic configuration diagram in the cross section A-A (cross section on a plane defined in the front-rear, upper-lower direction) of FIG. 1. FIG. 4 is a schematic configuration diagram in the cross section B-B (cross section on a plane defined in the front-rear, left-right direction) of FIG. 1. FIG. 5 is a schematic configuration diagram in the cross section C-C (cross section on a plane defined in the front-rear, left-right direction) of FIG. 1. In this embodiment, the tool holder 1 is applied to the turret 22 of a lathe 21, which is an example of a machine tool. The tool 24 has a substantially circular cross section and is provided with a tip 25 at its tip. The tool holder 1 includes a block-shaped base 2 fixed to the mounting surface 23 on the outer periphery of the swivel turret 22, and a sleeve 11 for gripping the tool 24. A tool insertion hole 3 into which the sleeve 11 and the tool 24 are inserted from the rear end is formed to penetrate in the front-rear direction in the base 2. On the left and right sides of the base 2 with the tool insertion hole 3 interposed therebetween, three base fixing bolts 4 for fixing the base 2 to the mounting surface 23 are arranged in the front-rear direction. At approximately the center in the vertical direction of the base 2 on the left side of the rear portion of the tool insertion hole 3, two tool fixing bolts 5 (fixing means) in the front-rear direction are screwed in the left-right direction.

[0012] The sleeve 11 coaxially has a tool fixing portion 13 provided with a fixing means avoidance port 12 at the rear side and a tool gripping portion 14 at the front side, and further includes a flange portion 15 for determining the retreat position in the axial direction of the sleeve 11 at the end face of the base 2. The tool fixing portion 13 and the tool gripping portion 14 are formed with an inner diameter that is equal to or smaller than the diameter of the tool 24. Further, a slit 16 is formed over the entire axial length above the tool gripping portion 14 and the flange portion 15. On the sleeve 11 on the left side of the slit 16, two sleeve expansion bolts 17 (expansion mechanism) capable of expanding the inner diameter of the tool gripping portion 14 by pressing the right surface of the slit 16 by a screwing operation are arranged in the front-rear direction and screwed in the left-right direction.

[0013] In the tool holder 1 configured as described above, when setting the tool, tighten the base fixing bolt 4 to fix the base 2 to the mounting surface 23 of the swivel turret 22. Next, tighten the sleeve expansion bolt 17 and press it against the right side of the slit 16 to expand the diameter of the tool gripping portion 14, and insert the tool 24 into the sleeve 11 from the rear end. Next, after adjusting the tool 24 to the desired protrusion length and angular position, loosen the sleeve expansion bolt 17 to bring the tool gripping portion 14 into contact with the tool 24. Next, insert the sleeve 11 and the tool 24 into the tool insertion hole 3 from the rear end. The inner diameter of the tool insertion hole 3 is formed larger than the outer diameter of the sleeve 11 excluding the flange portion 15 of the sleeve 11 in a state where the sleeve 11 holds the tool 24. Finally, tighten the tool fixing bolt 5, and the tool fixing bolt 5 passes through the fixing means avoidance port 12 and directly presses the tool 24 to fix the rear ends of the tool fixing portion 13 and the tool 24 to the base 2.

[0014] When performing turning with the tool 24 fixed to the tool holder 1 in this way, if machining vibration occurs, the tool holder 1 and the tool 24 are held and fixed with a high fixing force that does not cause relative movement at the tool fixing portion 13, and come into contact with a low fixing force that allows relative movement at the tool gripping portion 14. Further, since the tool gripping portion 14 is not tightened with bolts, the contact pressure is determined by the tightening allowance between the tool 24 and the sleeve 11 regardless of the operator's setting method, and performance variations can be suppressed. As a result, during machining, the position of the tool 24 does not change due to the firm fixing on the rear side of the tool holder 1, and stable friction damping occurs in the front contact region to suppress machining vibration.

[0015] As described above, according to the tool holder 1 and the lathe 21 of the above-described embodiment, the sleeve 11 has a fixing means avoidance port 12 that allows the tool fixing bolt 5 to directly apply a fixing force that restricts relative movement of the tool 24 with respect to the tool holder 1 when vibration due to machining occurs, and a tool gripping portion 14 that can hold the tool 24 with a fixing force lower than that of the tool fixing bolt 5 and allows relative movement of the tool 24 with respect to the tool holder 1 when vibration due to machining occurs. Therefore, even with a manufacturing cost comparable to that of existing split holders and the same setup man-hours, it is possible to stably impart a generally high damping property to any tool. Therefore, it is possible to obtain a stable and high vibration suppression effect while being low-cost and general-purpose, and to realize high-efficiency machining.

[0016] Hereinafter, modification examples of the tool holder will be described. However, since the configurations other than those shown in each modification example are the same as the above-described form, duplicate descriptions will be omitted and only different configurations will be described. The sleeve 11A shown in FIG. 6 is provided with a groove-shaped slit 16a that does not open to the outside and communicates with the tool gripping portion 14 in the front-rear direction on the opposite side of the slit 16 that sandwiches the tool gripping portion 14 in order to improve the opening property of the sleeve 11. A plurality of such slits that do not open to the outside may be provided. The sleeve 11B shown in FIG. 7 is also provided with a slit 16b that communicates with the tool gripping portion 14 and the flange portion 15 and opens to the outside in the front-rear direction on the right side of the tool gripping portion 14. The number of slits may be increased in this way. The sleeve 11C shown in FIG. 8 forms a vertical slit 16c that communicates with the slit 16 behind the flange portion 15 in addition to the front-rear direction. The sleeve 11D shown in FIG. 9 is a split mold 18 that separates the left side of the slit 16 from the forming portions of the tool gripping portion 14 and the flange portion 15 in order to facilitate the manufacture of the sleeve 11D. The sleeve 11D is formed by assembling the split mold 18 with bolts or the like. The number of such split molds may be increased. Also, the inner diameter of the split mold 18 may be different from that of the tool gripping portion 14. The sleeve 11E shown in FIG. 10 has the fixing means avoidance port 12e sized to allow the tool fixing bolt 5 to pass through with a minimum size. Also, the number of sleeve expansion bolts 17 is increased. The number of sleeve expansion bolts 17 may be appropriately changed in this way. The sleeve 11F shown in FIG. 11 has the largest size of the fixing means avoidance port 12f, that is, the tool fixing portion 13 is omitted. In this case, the rear right side of the tool gripping portion 14 substitutes for the role of the tool fixing portion 13. The base 2G shown in FIG. 12 is provided with bolt through-holes 6 for expanding the sleeve in order to loosen the sleeve expansion bolts 17 after inserting the sleeve 11 into the tool insertion hole 3.

[0017] On the other hand, in the above embodiment, the sleeve is provided with a slit that opens to the outside, but only slits that do not open to the outside may be provided to cause the same expansion deformation. In the above embodiment, the sleeve is deformed using the sleeve expansion bolts, but it goes without saying that it may be deformed using a spring, a lever, or the like. In the above embodiment, the sleeve is provided with a slit, but expansion deformation may be caused by thermal expansion without providing a slit. In the above embodiment, the tool fixing portion and the tool gripping portion are formed coaxially and with the same diameter, but they may be formed so that their centers are offset from each other, or they may have different diameters. The hole diameters of the tool fixing portion and the tool gripping portion and the cross-sectional shapes of both can be appropriately changed. In particular, the cross-sectional shape is not limited to a circle, and can be selected according to the cross-sectional shape of the tool, such as an ellipse or a polygon.

[0018] In the above embodiment, the tool fixing portion is arranged on the rear side and the tool gripping portion is arranged on the front side, but they may be arranged in the reverse order. The tool fixing portion may be arranged in the middle portion of the sleeve instead of the rear portion, and the tool gripping portion may be arranged on the front side or the rear side thereof. In the above embodiment, the sleeve expansion bolts are provided on the left side of the slit, but they may be provided on the right side of the slit. In the above embodiment, the fixing means avoidance port is provided on the left side of the sleeve, but it may be provided on the right side of the sleeve or on the lower side of the sleeve. In this case, the position of the tool fixing bolt is also changed according to the position of the fixing means avoidance port. In the above embodiment, the slit is provided on the upper side of the sleeve, but the angular position of the slit in the circumferential direction of the tool can be appropriately changed. In addition, the tool holder of the present disclosure can also be applied to machine tools other than lathes.

Description of Reference Numerals

[0019] 1,31··Tool holder, 2,2G··Base, 3,32··Tool insertion hole, 4··Base fixing bolt, 5··Tool fixing bolt, 6··Sleeve expansion bolt through hole, 11,11A~F··Sleeve, 12,12e~f··Fixing means avoidance port, 13··Tool fixing part, 14··Tool gripping part, 15··Flange part, 16,16a~16c,33··Slit, 17··Sleeve expansion bolt, 18··Split die, 21··Lathe, 22··Rotary turret, 23··Mounting surface, 24··Tool, 25··Chip, 34··Holder expansion bolt, 35··Holder fixing bolt, 36··Tool phase fixing bolt.

Claims

1. A tool holder provided on a machine tool for holding a tool, comprising: a sleeve for gripping the tool; a base having a tool insertion hole into which the sleeve is inserted together with the tool, and fixing means for fixing the tool and the sleeve inserted into the tool insertion hole; The sleeve has an avoidance opening for the fixing means through which the fixing means can directly apply a fixing force to the tool to restrict relative movement of the tool with respect to the tool holder when vibration due to machining occurs, and a tool gripping portion for gripping the tool with a fixing force lower than that of the fixing means and allowing relative movement of the tool with respect to the tool holder when vibration due to machining occurs. The tool holder is characterized by this.

2. The tool holder according to claim 1, wherein the tool gripping portion is provided on the tip side of the tool with respect to the avoidance opening for the fixing means.

3. The tool holder according to claim 1 or 2, wherein a cross-sectional shape perpendicular to the tool axis in the tool gripping portion is equal to or a similar shape smaller than the cross-sectional shape perpendicular to the tool axis in the tool.

4. The tool holder according to any one of claims 1 to 3, wherein a slit is formed in the sleeve along the axial direction of the tool insertion hole and communicates with at least the inner surface of the tool gripping portion and opens to the outside of the sleeve.

5. The tool holder according to claim 4, further comprising an expanding mechanism capable of expanding the tool gripping portion in the radial direction of the sleeve through the slit.

6. A machine tool comprising the tool holder according to any one of claims 1 to 5.

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