Stationary tool holder fixing mechanism

Abstract

To provide a fixing mechanism of a stationary tool holder capable of performing stable deep cutting.SOLUTION: A fixing mechanism of a stationary tool comprises: a first key (14) provided on an end surface of a spindle (11) of a machine tool (1); a first key groove (34) engaged with a first key; an engagement pin (17) provided in a housing (18); and an engagement hole (37) engaged with the engagement pin. Therein, engagement between the engagement pin and the engagement hole suppresses a tool holder (3) from rotating. When A is a width dimension of the first key is A, B is a width dimension of the first key groove of the tool holder with a tolerance in a range from b1 to b2, and C is a width dimension of a key groove of a standard tool holder with a tolerance in a range from c1 to c2, these width dimensions have a relation of C≥B>A and these tolerances have a relation of [c2-c1]>[b2-b1].SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fixing mechanism for a stationary tool holder, and more particularly to a fixing mechanism for a stationary tool holder used in a machine tool capable of selectively using a stationary tool and a rotary tool. [Background technology]

[0002] As disclosed in, for example, Japanese Patent Laid-Open No. 2004-142053 (Patent Document 1) and Japanese Utility Model Laid-Open No. 5-80636 (Patent Document 2), it is known that, for example, a key provided on the end face of a spindle of a machining center of a machine tool can be fitted into a key groove provided in a flange portion of a tool holder, thereby transmitting the rotational driving force of the spindle to the tool holder without slippage.

[0003] The dimensions and tolerances of machine tool keys and tool holder keyways are determined by their respective standards. For example, ISO12164-3 specifies the HSK-T shank as a standard for stationary tools. The HSK-T shank is a shank for stationary tools used in multitasking machines, which are machines that have both the functions of a machining center and a lathe. In this standard, the tolerances of the key and keyway are reduced to integrate the spindle and tool holder, suppressing changes in the phase of the cutting edge of the tool holder. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-142053 A [Patent Document 2] Japanese Utility Model Application Publication No. 5-80636 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, the opportunities for heavy cutting have been increasing. If the spindle is clamped so that it cannot rotate, heavy cutting can be performed using a standard HSK-T shank. However, in the case of small machine tools, it is mechanically difficult to provide a clamping mechanism. Therefore, if the spindle is not clamped so that it cannot rotate and the spindle servo lock function is turned off, the thrust from heavy cutting may rotate the tool holder together with the spindle. Also, even if the spindle servo lock function is turned on, the vibrations generated during cutting may cause micro-vibrations in the spindle and tool holder.

[0006] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a fixing mechanism for a stationary tool holder that is capable of performing stable heavy cutting. [Means for solving the problem]

[0007] For this purpose, a fixing mechanism for a stationary tool holder according to one aspect of the present invention is used in a machine tool capable of selectively using a stationary tool and a rotating tool, and includes a spindle having a pair of keys provided at positions symmetrical by 180°, a housing attached to the spindle, and a stationary tool holder having a key groove for the stationary tool holder manufactured with a manufacturing tolerance smaller than the manufacturing tolerance of the key groove for the rotating tool holder, and the fixing mechanism for the stationary tool holder fixes the stationary tool holder to the housing in a direction perpendicular to the rotation axis, the fixing mechanism for the stationary tool holder includes a first key provided on an end face of the spindle of the machine tool, a first key groove provided on a flange portion of the tool holder fixed to the spindle and engaging with the first key, and an engagement pin provided in a housing supporting the spindle, and an engagement hole provided in the tool holder which engages with the engagement pin, and rotation of the tool holder is suppressed by engagement between the engagement pin and the engagement hole, when a width dimension of the first key is A, a width dimension of the first key groove of the tool holder is B and its tolerance is in the range from b1 to b2, and a width dimension of the key groove of the standardized tool holder is C and its tolerance is in the range from c1 to c2, the width dimensions of the first key, the key groove of the standardized tool holder, and the first key groove of the tool holder satisfy a relationship of C≧B>A, and the tolerances of the key groove of the standardized tool holder and the first key groove of the tool holder satisfy a relationship of [c2-c1]>[b2-b1].

[0008] Preferably, the engagement pin is provided movable in a direction perpendicular to the rotation axis of the tool holder.

[0009] Preferably, the engagement pin includes a tapered shape narrowing toward the axial tip side, and the engagement hole includes a tapered hole having the same angle as the tapered shape of the engagement pin.

[0010] Preferably, the engagement pin includes a tapered shape that narrows toward the axial tip side, and is supported so as to be axially movable via a housing attached to the housing, and the housing includes a tapered hole with the same angle as the tapered shape of the engagement pin.

[0011] Preferably, the device further includes a judgment unit which judges whether or not the engagement pin and the engagement hole are engaged, and a control unit which mechanically controls the rotation of the spindle of the machine tool in response to the judgment unit determining that the engagement pin and the engagement hole are engaged.

[0012] Preferably, the tool holder further includes a second key located circumferentially at a position 180° from the first key and a second key groove engaging with the second key, and the width dimension and tolerance of the second key are the same as those of a standard tool holder.

[0013] Preferably, the second key has a length in the rotation axis direction longer than that of the first key.

[0014] Preferably, the second key includes a tapered tip, and the second keyway is tapered at its receiving end to receive the second key.

[0015] Preferably, the engagement pin is supported axially movably via a casing attached to the housing, and the casing is attached to the housing so that its position can be adjusted in the axial direction.

[0016] Preferably, the device further includes an alignment mechanism for aligning the center of the engagement pin with the center of the engagement hole. Effect of the Invention

[0017] According to the present invention, stable heavy cutting can be performed. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a front view showing a fixing mechanism of the stationary tool holder according to the first embodiment. [Diagram 2] FIG. 2 is a front view showing the fixing mechanism for the stationary tool holder according to the first embodiment, showing a state in which the tool holder has been removed from the machine tool. [Diagram 3] FIG. 3 is a bottom view of the spindle end surface as viewed from the arrow III in FIG. 2. [Figure 4]FIG. 4 is a side view of the first key, taken along the arrow IV in FIG. 3; [Diagram 5] 4 is a side view of the second key as seen from the arrow V in FIG. 3. [Figure 6] This figure shows JIS standard B6340, where (A) is a cross-sectional view and a bottom view of the standard product, and (B) is an excerpt of the width dimensions and tolerances of BT30 from the standard table. [Figure 7] 7 is a plan view of the tool holder as viewed from the arrow VII in FIG. 2. [Figure 8] 8 is a side view of the first keyway as viewed from the arrow VIII in FIG. 7. [Figure 9] 8 is a side view of the second keyway as viewed from the arrow IX in FIG. 7. [Figure 10] This figure shows MAS BT standard 403-1982, where (A) is a front view and a plan view of the standard product, and (B) is an excerpt of the width dimensions and tolerances of BT30 in the standard table. [Figure 11] FIG. 2 is a schematic diagram showing a relationship between a first key and a first key groove, and a relationship between a second key and a second key groove. [Figure 12] FIG. 11 is a front view showing a fixing mechanism of a stationary tool holder according to a second embodiment. [Figure 13] FIG. 11 is a front view showing a fixing mechanism of a stationary tool holder according to a third embodiment. [Figure 14] FIG. 13 is a front view showing a fixing mechanism of a stationary tool holder according to a fourth embodiment. [Figure 15] 15A and 15B are diagrams showing a fixing mechanism of a stationary tool holder according to a fifth embodiment, in which (A) is a front view and (B) is a plan view of a housing as seen from the arrow XVb in FIG. 15A. [Figure 16] FIG. 13 is a front view showing a fixing mechanism of a stationary tool holder according to a sixth embodiment. [Figure 17] FIG. 17 is an enlarged view of the circled portion in FIG. 16. [Figure 18] FIG. 23 is a side view of a tool holder body according to the sixth embodiment. [Figure 19] FIG. 23 is a perspective view showing a part of an alignment mechanism according to the sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and their description will not be repeated.

[0020] <Embodiment 1> A fixing mechanism for a stationary tool holder according to a first embodiment of the present invention will be described with reference to Figs. 1 and 2. The dashed line O in Figs. 1 and 2 indicates the rotation axis of the machine tool, and the dashed line O in Fig. 1 indicates the rotation axis of a workpiece that is an object to be turned. Fig. 2 is a diagram showing the tool holder in Fig. 1 removed from the spindle of the machine tool. In the front views of Figs. 1 and 2, the machine tool is shown in cross section for ease of understanding.

[0021] The fixing mechanism for the stationary tool holder is used in a machine tool 1 that can selectively use a stationary tool and a rotating tool, and is particularly intended for fixing a stationary tool for turning on the machine tool 1. The fixing mechanism for the stationary tool holder includes a spindle having a pair of keys provided at positions symmetrical at 180°, a housing attached to the spindle, and a stationary tool holder having a keyway for the stationary tool holder manufactured with a manufacturing tolerance smaller than that of the keyway for the rotated tool holder, and fixes the stationary tool holder to the housing in a direction perpendicular to the axis of rotation.

[0022] A stationary tool attached to a machine tool 1 performs turning on a workpiece 100, which is a workpiece rotating at high speed. Prior to describing the fixing mechanism of the stationary tool holder, a detailed description will be given of the machine tool 1 and the stationary tool holder 3. In the following description, the stationary tool holder 3 will be simply referred to as the tool holder 3.

[0023] (About machine tools) The machine tool 1 is, for example, a composite machine having the functions of both a machining center and a lathe. The machine tool 1 generally includes a spindle head 10 and a spindle 11 that is rotatably mounted relative to the spindle head 10. The spindle head 10 and the spindle 11 are connected via a plurality of bearings 13. This allows the spindle 11 to be rotatable relative to the fixed spindle head 10.

[0024] The spindle 11 is provided with a tapered hole 12 along the rotation axis of the spindle 11. The tapered hole 12 is a hole for mounting a tool holder 3, which will be described later, and is tapered upward. A pair of keys 14, 15 (see FIG. 3 for the keys 15) are provided on the end face of the spindle 11, facing each other in the circumferential direction. The pair of keys 14, 15 are provided at positions 180° apart in the circumferential direction. The pair of keys 14, 15 engage with key grooves 34, 35, which will be described later (see FIG. 7 for the key groove 35). Although the keys 14, 15 are located on the end face of the spindle 11, the key 14 located on the front side is shown with light ink in FIG. 1 and FIG. 2 for easy understanding. The keys 14, 15 will be described later.

[0025] A housing 18 is attached to the side of the spindle head 10. The lower end of the housing 18 is located lower than the lower end of the spindle head 10 by the height dimension of a flange portion 32 of the tool holder 3, which will be described later. This provides a step between the housing 18 and the spindle head 10. The spindle head 10, which rotatably supports the spindle 11, may be included in the housing.

[0026] A case 16 is attached to the lower end of the housing 18. An engagement pin 17 is provided inside the case 16 so as to be movable in a direction perpendicular to the axis of rotation of the tool holder. A cylinder chamber, for example, is provided inside the case 16, and a piston serving as the engagement pin 17 is converted into linear motion in a direction perpendicular to the axis of rotation (left-right direction) by air or hydraulic pressure. The engagement pin 17 will be described later.

[0027] (About tool holders) The tool holder 3 is a stationary tool and is used when performing turning on a rotating workpiece 100. As shown in Fig. 2 in particular, the tool holder 3 generally comprises a tapered shank portion 30, a flange portion 32, and a tool holder body 36. The tapered shank portion 30 has the same inclination as the tapered hole 12 provided in the spindle 11 of the machine tool 1. A pull stud 31 is provided at the tip of the tapered shank portion 30, and the tapered shank portion 30 is pulled into the tapered hole 12 by the pull stud 31 and clamped.

[0028] A flange portion 32 is provided at the lower end of the tapered shank portion 30. The flange portion 32 is located in the center in the direction of the rotation axis and protrudes in the outer diameter direction. The flange portion 32 is provided with key grooves 34, 35 that engage with the keys 14, 15 of the machine tool 1 described above (see FIG. 7 for the key groove 35). The key grooves 34, 35 are recesses that open downward from the upper edge of the flange portion 32. The key grooves 34, 35 will be described later.

[0029] A tool holder body 36 is provided at the lower end of the flange portion 32. A cutting tip 38 for performing turning on the workpiece 100 is attached to the lower end of the tool holder body 36. The cutting tip 38 protrudes laterally from the side wall of the tool holder body 36. An engagement hole 37 is provided at a position 180° circumferentially relative to the cutting tip 38. The engagement hole 37 will be described later.

[0030] (Regarding the fixing mechanism of stationary tool holder) Next, the fixing mechanism of the stationary tool holder will be described in detail with further reference to Fig. 3 to Fig. 11. The fixing mechanism of the stationary tool holder is established by at least two engagement points. Specifically, the fixing mechanism of the stationary tool holder includes the above-mentioned keys 14, 15, key grooves 34, 35, engagement pin 17, and engagement hole 37. The keys 14, 15 engage with the key grooves 34, 35, and the engagement pin 17 engages with the engagement hole 37.

[0031] Prior to describing the keys 14, 15 and the key grooves 34, 35, a description will be given of the engagement pin 17 and the engagement hole 37. Referring to Figures 1 and 2, the engagement pin 17 engages with the engagement hole 37, and the engagement between the engagement pin 17 and the engagement hole 37 restricts the rotation of the tool holder 3.

[0032] The engagement pin 17 is rod-shaped and extends in the left-right direction, and has a flat, angular tip corner without a radius. The engagement hole 37 is a recess having a depth sufficient to receive the tip of the engagement pin 17. The engagement hole 37 has an angular shape that corresponds to the shape of the tip of the engagement pin 17.

[0033] Next, the keys 14 and 15 will be described with further reference to Figures 3 to 6. Figure 3 is a view seen from the arrow III in Figure 2 and is a bottom view of the end face of the spindle 11 of the machine tool 1, Figure 4 is a view seen from the arrow IV in Figure 3 and is a side view showing the first key 14, and Figure 5 is a view seen from the arrow V in Figure 3 and is a side view showing the second key 15. Figure 6 is a diagram showing B6340 of the JIS standard.

[0034] As described above, the keys 14, 15 are provided on the end face of the spindle 11 of the machine tool 1. As shown in Fig. 3, the first key 14 and the second key 15 are provided facing each other at positions 180° apart in the circumferential direction.

[0035] The first key 14 shown in FIG. 4 has a width dimension A and a tolerance in the range of a1 to a2. This width dimension and tolerance are defined by JIS standard B6340 shown in FIG. 6. According to FIG. 6, the width dimension b defined by JIS standard B6340 is 15.9 mm and the tolerance is in the range of −0.008 mm to 0 mm. That is, the width dimension A of the first key 14 in this embodiment is 15.9 mm, the tolerance a1 is −0.008 mm, and the tolerance a2 is 0 mm. The length (height) of the first key 14 in the rotation axis direction is D.

[0036] The second key 15 shown in FIG. 5 has a tapered shape whose tip narrows downward. The second key 15 includes a tapered lower portion 15a and an upper portion 15b extending upward in parallel from the lower portion 15a. The boundary between the lower portion 15a and the upper portion 15b is located midway in the vertical direction of the second key 15. The upper portion 15b of the second key 15 is formed with the same width dimension and tolerance as the first key 14. That is, the width dimension A is 15.9 mm, the tolerance a1 is −0.008 mm, and the tolerance a2 is 0 mm. Naturally, since the lower portion 15a is tapered, the width dimension of the lower portion 15a is smaller than the width dimension of the upper portion 15b.

[0037] The length (height) of the second key 15 in the rotation axis direction is E, the height of the lower part 15a is E1, and the height of the upper part 15b is E2. The height E2 of the upper part 15b is the same as the height D of the first key 14 described above. In other words, the height E of the second key 15 is greater than the height D of the first key 14.

[0038] Next, the keyways 34, 35 will be described with reference to Figures 7 to 10. Figure 7 is a view seen from the arrow VII in Figure 2 and is a plan view of the tool holder 3, Figure 8 is a view seen from the arrow VIII in Figure 7 and is a side view showing the first keyway 34, and Figure 9 is a view seen from the arrow IX in Figure 7 and is a side view showing the second keyway 35. Figure 10 is a diagram showing 403-1982 of the MAS BT standard.

[0039] 7, the keyways 34, 35 are provided in a flange portion 32 of a tool holder 3 fixed to a spindle 11. The keyways 34, 35 are provided at positions spaced 180° apart in the circumferential direction.

[0040] As shown in Fig. 8, the first keyway 34 is recessed downward from the upper end edge of the flange portion 32. The first keyway 34 is recessed, and the lower end may be rounded. The first keyway 34 has a width dimension B and a tolerance in the range of b1 to b2. This width dimension and tolerance are set to be narrower and smaller than those stipulated by MAS BT standard 403-1982 shown in Fig. 10.

[0041] According to FIG. 10, the width dimension b defined in 403-1982 of the MAS BT standard is 16.1 mm, and the tolerance is in the range of 0 mm to +0.18 mm. That is, the width dimension C of the keyway of the standard tool holder in this embodiment is 16.1 mm, the tolerance c1 is 0 mm, and the tolerance c2 is +0.18 mm. In contrast, the first keyway 34 is narrower than the width dimension defined in the MAS standard, and the tolerance is minimized. Specifically, the width dimension B of the first keyway 34 is 15.9 mm. This width dimension B is the same as the width dimension A of the first key 14 in units of 100 μm, but is larger than the width dimension A of the first key 14 in units of less than 100 μm. The tolerance of the first key groove 34 is set in the range of +0.04 mm to +0.06 mm, that is, the tolerance b1 is set to +0.04 mm and the tolerance b2 is set to +0.06 mm or less.

[0042] The second keyway 35 shown in FIG. 9 is recessed from the upper end to the lower end of the flange portion 32, like the first keyway 34, but has a shape that opens wide at the top, and its receiving end is formed in a tapered shape to receive the second key 15. Specifically, the second keyway 35 includes an upper wall 35a that narrows from the top to the bottom, and a lower wall 35b that continues downward from the upper wall 35a. The width dimension between the upper walls 35a is larger than the width dimension between the lower walls 35b. The width dimension of the lower wall 35b of the second keyway 35 is formed with the width dimension and tolerance defined in the above-mentioned MAS BT standard 403-1982. That is, the width dimension C of the lower wall 35b is 16.1 mm, and the tolerance is in the range of 0 mm to +0.18 mm, that is, the tolerance c1 is 0 mm or more, and the tolerance c2 is +0.18 mm or less.

[0043] From the above, when the width dimension of the first key 14 and the second key 15 is A, the width dimension of the second key groove 35 is C, and the width dimension of the first key groove 34 is B, the relationship of the width dimensions C≧B>A is established. Furthermore, when the tolerance of the first key groove 34 is in the range of c1 to c2, and the tolerance of the second key groove 35 is in the range of b1 to b2, the relationship of the tolerances is [c2-c1]>[b2-b1] is established. In other words, the width dimension of the first key groove 34 is narrower than the width dimension of the key groove of the standard product, and the tolerance of the first key groove 34 is smaller than the tolerance of the key groove of the standard product, making it extremely small.

[0044] Fig. 11 is a diagram showing the relationship between the first key 14 and the first key groove 34, and the relationship between the second key 15 and the second key groove 35. The relationship between the keys 14, 15 and the key grooves 34, 35 will be described with reference to Fig. 11.

[0045] The first key 14 is a standard product of the above-mentioned JIS standard. In contrast, the first key groove 34 with which the first key 14 engages has a narrower width dimension and a much smaller tolerance than the above-mentioned standard product of the HSK standard. Therefore, by engaging the first key 14 with the first key groove 34, the spindle 11 and the tool holder 3 can be integrated more easily than if a standard key groove were used.

[0046] The second key 15 is a JIS-standard product, but has a tapered lower portion 15a at its tip. Furthermore, the second key groove 35 with which the second key 15 engages has the same width dimension C between the lower walls 35b as the HSK-standard product, but the width dimension between the upper walls 35a is larger than that of the lower walls 35b. Therefore, even if the center position of the second key 15 and the center position of the second key groove 35 are slightly misaligned, the tapered lower portion 15a of the second key 15 is received by the upper wall 35a of the second key groove 35, so that the second key 15 and the second key groove 35 can engage with each other. In this way, the second key 15 and the second key groove 35 function as a guide to guide the second key 15 to the center position when it is inserted.

[0047] By narrowing the width dimension of the first key groove 34 and minimizing the tolerance, the gap between the first key groove 34 and the first key 14 can be reduced, so that the machine tool 1 and the tool holder 3 can be integrated. However, if the width dimension of the second key groove 35 as well as the first key groove 34 is narrower than that of the standard product and the tolerance is minimized, alignment becomes difficult, and it may be difficult for the second key 15 to fit into the second key groove 35. Therefore, by making the second key groove 35 have the width dimension and tolerance of the conventional standard product, the second key 15 fits into the tapered shape of the lower wall 35b of the second key groove 35, and the second key 15 is guided to the center of the second key groove 35, so that the first key 14 can be easily engaged with the first key groove 34 with a narrow width dimension and a small tolerance.

[0048] The fixing mechanism of the stationary tool holder in this embodiment is engaged by a pair of keys 14, 15 and a pair of key grooves 34, 35, but by making one of the key grooves have the width dimension and tolerance of the standard product and making the other key groove smaller than the width dimension and tolerance of the standard product, one key groove (the standard product) with the same width dimension and tolerance as the standard product acts as a guide to facilitate engagement of the other key groove, which has a narrower width dimension and a minimal tolerance than the standard product. Thus, this embodiment is characterized in that the width dimensions and tolerances of the pair of key grooves are different rather than the same.

[0049] Furthermore, the height E of the second key 15 is formed to be longer than the height D of the first key 14 by the height E1 of the tapered lower portion 15a. As a result, when the tool holder 3 is attached to the spindle 11, the second key 15 having a guiding function is inserted into the second key groove 35 before the first key 14 having a positioning function is inserted into the first key groove 34, so that the second key 15 can be guided to the center of the second key groove 35.

[0050] From the above, the fixing mechanism of the stationary tool holder of this embodiment can integrate the spindle 11 and the tool holder 3 by the engagement between the keys 14, 15 and the key grooves 34, 35, and can integrate the housing 18 and the tool holder 3 by the engagement between the engagement pin 17 and the engagement hole 37, so that there is no risk of the tool holder 3 rotating during heavy cutting and no micro-vibrations are generated, making it possible to perform stable heavy cutting. Also, the keys 14, 15 and the key grooves 34, 35 are engaged in the direction of the rotation axis, while the engagement pin 17 and the engagement hole 37 are engaged in the direction perpendicular to the direction of the rotation axis, so that the engagement directions are different. In this respect as well, the integration of the machine tool 1 and the tool holder 3 can be strengthened.

[0051] <Embodiment 2> A fixing mechanism for a stationary tool holder according to a second embodiment of the present invention will be described with reference to Fig. 12. Fig. 12 is a front view showing a fixing mechanism for a stationary tool holder according to the second embodiment. The first and second embodiments are different from each other in the shape of the tip of the engagement pins 17, 17A and the shape of the engagement holes 37, 37A. Only the differences from the structure shown in the first embodiment will be described below.

[0052] The tip of the engagement pin 17A in this embodiment is tapered toward the tip in the axial direction. In contrast, the engagement hole 37A is a tapered hole with the same angle as the tapered shape of the engagement pin 17A. The tip of the engagement pin 17A is not sharp but is flat, and the bottom of the engagement hole 37A is flat corresponding to the tip of the engagement pin 17A.

[0053] This provides a tapered connection between the engagement pin 17A and the engagement hole 37A, further improving rigidity. Furthermore, even if the center position of the engagement pin 17A is misaligned with the center position of the engagement hole 37A, the engagement pin 17A can be inserted into the engagement hole 37A.

[0054] <Embodiment 3> A fixing mechanism for a stationary tool holder according to a third embodiment of the present invention will be described with reference to Fig. 13. Fig. 13 is a front view showing a fixing mechanism for a stationary tool holder according to the third embodiment. The second and third embodiments differ from each other in the locations where the tapered shapes of the engagement pins 17A and 17B are provided. Only the differences from the structure shown in the second embodiment will be described below.

[0055] In this embodiment, a tapered portion 20B is provided at a longitudinal midpoint of the engagement pin 17B, the tapered portion 20B being tapered toward the axial tip. The tapered portion 20B is provided along the entire outer circumference of the engagement pin 17B. The engagement pin 17B is narrower on the tool holder 3 side and wider on the cylinder side, with the tapered portion 20B as the boundary. The tip of the engagement pin 17B is flat like the engagement pin 17 in the first embodiment, and does not have to be tapered like the engagement pin 17A in the second embodiment.

[0056] Housing 16B includes tapered hole 19B with the same angle as tapered portion 20B of engagement pin 17B. Tapered hole 19B is provided at a position that abuts tapered portion 20B when engagement pin 17B is engaged with engagement hole 37. In the present embodiment as well, tapered portion 20B of engagement pin 17B and tapered hole 19B of housing 16B are tapered together, thereby further improving rigidity.

[0057] <Fourth embodiment> A fixing mechanism for a stationary tool holder according to a fourth embodiment of the present invention will be described with reference to Fig. 14. Fig. 14 is a front view showing a fixing mechanism for a stationary tool holder according to the fourth embodiment. The first and fourth embodiments are different in that a proximity switch 21C is provided. Only the differences from the structure shown in the first embodiment will be described below.

[0058] In this embodiment, a proximity switch 21C is provided at a location located at the rear end of engagement pin 17. Proximity switch 21C electrically locks the rotation of spindle 11 of machine tool 1 when engagement pin 17 is engaged with engagement hole 37. Specifically, proximity switch 21C is an interlock, and includes a determination unit and a control unit, not shown. The determination unit determines whether or not engagement pin 17 and engagement hole 37 are engaged. The control unit electrically controls the rotation of spindle 11 of machine tool 1 in response to the determination by the determination unit that engagement pin 17 and engagement hole 37 are engaged.

[0059] Proximity switch 21C is provided to prevent spindle 11 of machine tool 1 from rotating accidentally during turning. According to this embodiment, in addition to keys 14, 15 and key grooves 34, 35, engagement pin 17 and engagement hole 37, spindle 11 of machine tool 1 can be electrically controlled to prevent it from rotating.

[0060] <Embodiment 5> A fixing mechanism for a stationary tool holder according to a fifth embodiment of the present invention will be described with reference to Fig. 15(A) and Fig. 15(B). Fig. 15(A) is a front view showing the fixing mechanism for a stationary tool holder according to the fifth embodiment, and Fig. 15(B) is a plan view showing only the housing. The first and fifth embodiments are different in the method of attaching the housing 16D. Only the differences from the structure shown in the first embodiment will be described in detail below.

[0061] The housing 16 of the first embodiment described above was fixed so as not to move relative to the housing 18. In contrast, the housing 16D of the present embodiment is attached to the housing 18 via the elongated holes 40D, the mounting bolts 41D, and the adjustment pins 42D. As shown in FIG. 15(B), the elongated holes 40D are provided at four corners of the upper surface of the housing 16D and extend in a direction perpendicular to the rotation axis. As shown in FIG. 15(A), the mounting bolts 41D penetrate the elongated holes 40D from below to above. The adjustment pins 42D extend in a direction perpendicular to the rotation axis, penetrate the side walls 22D of the housing 18D, and abut against the sides of the housing 16D. As a result, the housing 16D is fixed to the housing 18 so as to be movable in the left-right direction.

[0062] As shown in Fig. 1, when the engagement pin 17 is engaged with the engagement hole 37, stress is applied to the tool holder 3 and the spindle 11, which may displace the tool holder 3 and move the cutting tip 38 from a predetermined position. This may result in insufficient precision cutting of the workpiece 100. Furthermore, a load may be applied to the bearing 13 of the spindle 11.

[0063] Therefore, in this embodiment, a dial gauge 101D for measuring the position of the cutting tip 38 is disposed on the tool holder body 36. The engagement pin 17 is engaged with the engagement hole 37, and the position of the tool holder body 36 is measured by the dial gauge 101D. When it is determined that the position is correct, the positions of the casing 16D and the housing 18D are fixed by the adjustment pin 42D.

[0064] In this embodiment, the case 16D is attached to the housing 18D via the elongated holes 40D, the mounting bolts 41D, and the adjustment pins 42D, so that it is possible to prevent the engagement pins 17 from pressing the tool holder 3 more than necessary, thereby preventing the tool holder 3 from being displaced, thereby enabling more precise cutting.

[0065] <Sixth embodiment> A fixing mechanism of a stationary tool holder according to a sixth embodiment of the present invention will be described with reference to Figs. 16 to 19. Fig. 16 is a side view showing the fixing mechanism of a stationary tool holder according to the sixth embodiment, Fig. 17 is an enlarged view of the circled portion of the dashed line in Fig. 16, Fig. 18 is a side view showing an engagement hole, and Fig. 19 is a perspective view showing an alignment mechanism. The second and sixth embodiments are common in that the tips of the engagement pins 17, 17E are tapered, but are different in that the sixth embodiment has an alignment mechanism 60E. Only the differences from the structure shown in the first embodiment will be described in detail below.

[0066] In this embodiment, an alignment mechanism 60E is provided for aligning the center of the engagement pin 17E with the center of the engagement hole 37E. The alignment mechanism 60E is sandwiched between the engagement pin 17E and the engagement hole 37E. As shown in FIG. 17 and FIG. 19, the alignment mechanism 60E includes a plate-shaped portion 61E and a cylindrical portion 62E protruding from the plate-shaped portion 61E toward the tool holder 3. The plate-shaped portion 61E is provided with four elongated holes 64E and four mounting bolts 65E that pass through the elongated holes 64E to fix the alignment mechanism 60E to the tool holder body 36E. In FIG. 19, the four elongated holes 64E extend along the horizontal direction of the plate-shaped portion 61E, but may extend vertically.

[0067] The positioning mechanism 60E aligns the center of the engagement pin 17E with the center of the engagement hole 37E. The positioning mechanism 60E is also called a centering mechanism. The positioning mechanism 60E is supported movably relative to the tool holder body 36E by fixing the plate-shaped portion 61E to the tool holder body 36E by the long hole 64E and the mounting bolt 65E. A hole portion 63E that engages with the engagement pin 17E is formed in the plate-shaped portion 61E and the cylindrical portion 62E. The hole portion 63E is a bottomed hole, has the same shape as the engagement pin 17E, and is a tapered hole with the same angle as the tapered shape of the engagement pin 17E. The cylindrical portion 62E is smaller than the engagement hole 37E because it is supported movably within the engagement hole 37E.

[0068] 17 and 18, a recess 51E and four mounting holes 52E are provided in the recess 51E at the contour portion between the engagement hole 37E and the tool holder body 36. As shown in Fig. 18, the recess 51E is an area where the plate-shaped portion 61E of the alignment mechanism 60E is located, and has substantially the same rectangular shape as the plate-shaped portion 61E in a side view. The recess 51E is larger than the shape of the plate-shaped portion 61E in order to movably support the plate-shaped portion 61E.

[0069] For example, the following concerns arise when the tip of engagement pin 17A is tapered as in embodiment 2. Specifically, if engagement pin 17A is misaligned in the radial or vertical direction with respect to the center of engagement hole 37A, and tool holder 3 is pressed hard when engaging engagement pin 17A with engagement hole 37A, tool holder 3 may be rotated along the direction of the tapered tip of engagement pin 17A, causing a change in the phase of the tool holder and the spindle.

[0070] In contrast, in this embodiment, an alignment mechanism 60E is provided between the engagement pin 17E and the engagement hole 37E to align the center of the engagement pin with the center of the engagement hole. Specifically, the recess 51E is made larger than the plate-shaped portion 61E, and the engagement hole 37E is made larger than the cylindrical portion 62E, so that the engagement pin 17E can move in the radial direction or the up-down direction by the length of the long hole 64E. Therefore, the center of the engagement pin 17E can be aligned with the center of the engagement hole 37E.

[0071] <About modified examples> In the fixing mechanism of the stationary tool holder in the first embodiment, the keys 14, 15 and the keyways 34, 35 are provided at positions 180° apart in the circumferential direction, the second keyway 35 has a width dimension C of the standard product and a tolerance in the range of c1 to c2, and the first keyway 34 has a width dimension B narrower than the width dimension C of the standard product and a tolerance in the range of b1 to b2 that is extremely small compared to the tolerance of the standard product, but both of the two keyways 34, 35 may be narrower than the width dimension of the standard product and have extremely small tolerances. By making the width dimension of both keyways 34, 35 narrower than the width dimension of the standard product and making the tolerance extremely small, the spindle 11 and the tool holder 3 can be more integrated, making it possible to perform more stable heavy turning.

[0072] 9, the second key groove 35 in the first embodiment has a shape that opens widely at the top, but may have the same shape as the first key groove 34 and is not limited to this shape. Also, the second key 15 in the first embodiment has a shape that is taller than the first key 14, but for example, the second key 15 and the first key 14 may have approximately the same height.

[0073] In the above embodiment, the fixing mechanism of the stationary tool holder is provided with two keys and two key grooves. However, the present invention is not limited to this configuration. For example, the fixing mechanism may have only one key and one key groove, or may have three or more keys and key grooves. The numbers of keys and key grooves are not limited.

[0074] In the above embodiment, the engagement pin is provided so as to be movable in a direction perpendicular to the rotation axis of the tool holder 3. However, the movement direction is not limited to this direction. For example, the engagement pin may be provided so as to be movable in the direction of the rotation axis, that is, so as to be movable in the vertical direction.

[0075] Although the embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited to the illustrated embodiment. Various modifications and variations can be made to the illustrated embodiment within the same scope as the present invention or within an equivalent scope. [Industrial Applicability]

[0076] The present invention is advantageously used in a machine tool that is capable of selectively using a stationary tool and a rotating tool. [Explanation of symbols]

[0077] 1 machine tool, 3 stationary tool holder (tool holder), 11 spindle, 14 first key, 15 second key, 16, 16B, 16D housing, 17, 17A, 17B, 17E engagement pin, 18, 18D housing, 32 flange portion, 34 first key groove, 35 second key groove, 37, 37A, 37B, 37E engagement hole, 40E alignment mechanism.

Claims

1. A fixing mechanism for a stationary tool holder used in a machine tool capable of selectively using a stationary tool and a rotating tool, the fixing mechanism comprising: a spindle having a pair of keys provided at positions symmetrical at 180°; a housing attached to the spindle; and a stationary tool holder having a key groove for the stationary tool holder manufactured with a manufacturing tolerance smaller than that of a key groove for a rotating tool holder, the fixing mechanism fixing the stationary tool holder to the housing in a direction perpendicular to a rotation axis, a first key which is one of the pair of keys and is provided on an end surface of a spindle of the machine tool; a first key groove provided in a flange portion of a tool holder fixed to the spindle and adapted to engage with the first key; an engagement pin provided in the housing and movable in a direction perpendicular to a rotation axis of the tool holder; an engagement hole provided in the tool holder and engaging with the engagement pin; The engagement pin and the engagement hole are engaged to restrict rotation of the tool holder, The width dimension of the first key is A, The width dimension of the first keyway of the tool holder is B, and the tolerance of the width dimension is in the range of b1 to b2, If the width dimension of the keyway of a standard tool holder is C and its tolerance is in the range of c1 to c2, the first key, the key groove of the standard tool holder, and the first key groove of the tool holder have width dimensions that satisfy the relationship C≧B>A; the tolerances of the key groove of the standard tool holder and the first key groove of the tool holder satisfy the relationship [c2-c1]>[b2-b1], The engagement pin is supported axially movably via a casing attached to the housing, A fixing mechanism for a stationary tool holder, wherein the casing is attached to the housing so that its position can be adjusted in a direction perpendicular to the rotation axis.

2. A fixing mechanism for a stationary tool holder used in a machine tool capable of selectively using a stationary tool and a rotating tool, the fixing mechanism comprising: a spindle having a pair of keys provided at positions symmetrical at 180°; a housing attached to the spindle; and a stationary tool holder having a key groove for the stationary tool holder manufactured with a manufacturing tolerance smaller than that of a key groove for a rotating tool holder, the fixing mechanism fixing the stationary tool holder to the housing in a direction perpendicular to a rotation axis, a first key which is one of the pair of keys and is provided on an end surface of a spindle of the machine tool; a first key groove provided in a flange portion of a tool holder fixed to the spindle and adapted to engage with the first key; An engagement pin provided on the housing; an engagement hole provided in the tool holder and engaging with the engagement pin; The engagement pin and the engagement hole are engaged to restrict rotation of the tool holder, The width dimension of the first key is A, The width dimension of the first keyway of the tool holder is B, and the tolerance of the width dimension is in the range of b1 to b2, If the width dimension of the keyway of a standard tool holder is C and its tolerance is in the range of c1 to c2, the first key, the key groove of the standard tool holder, and the first key groove of the tool holder have width dimensions that satisfy the relationship C≧B>A; the tolerances of the key groove of the standard tool holder and the first key groove of the tool holder satisfy the relationship [c2-c1]>[b2-b1], a second key which is the other of the pair of keys and is provided at a position 180° circumferentially with respect to the first key, and a second key groove which engages with the second key; The width dimension and tolerance of the second key are the same as those of the standard tool holder; In a state where the first key is engaged with the first key groove and the second key is engaged with the second key groove, The length of the second key in the direction of the rotation axis is longer than that of the first key, A fixing mechanism for a stationary tool holder, wherein a position of the spindle side end of the first key is the same as a position of the spindle side end of the second key.

3. The fixing mechanism for a stationary tool holder according to claim 2 , wherein the engagement pin is provided so as to be movable in a direction perpendicular to a rotation axis of the tool holder.

4. The engagement pin includes a tapered shape that narrows toward a tip end side in an axial direction, The fixing mechanism of a stationary tool holder according to claim 1 or 2, wherein the engagement hole includes a tapered hole having the same angle as a tapered shape of the engagement pin.

5. the engagement pin includes a tapered shape narrowing toward a tip end side in the axial direction, and is supported movably in the axial direction via the casing attached to the housing, The stationary tool holder locking mechanism of claim 1 , wherein the housing includes a tapered hole engageable with the tapered shape of the engagement pin and having the same angle as the tapered shape of the engagement pin.

6. a determination unit that determines whether the engagement pin and the engagement hole are in an engaged state; 3. The fixing mechanism of a stationary tool holder according to claim 1, further comprising: a control unit that electrically controls rotation of a spindle of the machine tool in response to the determination by the determination unit that the engagement pin and the engagement hole are engaged with each other.

7. the second key includes a tapered tip; The stationary tool holder locking mechanism of claim 2 , wherein the second keyway is tapered at a receiving end thereof to receive the second key.

8. The engagement pin is supported axially movably via a casing attached to the housing, The fixing mechanism for a stationary tool holder according to claim 1 or 2, wherein the casing is attached to the housing so as to be positionably adjustable in a direction perpendicular to the rotation axis.

9. The fixing mechanism of a stationary tool holder according to claim 1 or 2, further comprising an alignment mechanism for aligning a center of the engagement pin with a center of the engagement hole.

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