JP7675767B2 - Stationary tool holder fixing mechanism - Google Patents

Description

This invention relates to a fixing mechanism for a stationary tool holder, and in particular to a fixing mechanism for a stationary tool holder used in a machine tool that can selectively use a stationary tool and a rotating tool.

As disclosed in JP 2004-142053 A (Patent Document 1) and JP 5-80636 A (Patent Document 2), for example, it is known that the rotational drive force of the spindle can be transmitted to the tool holder without slippage by fitting a key provided on the end face of the spindle of a machining center of a machine tool into a key groove provided in a flange portion of the tool holder.

The dimensions and tolerances of machine tool keys and tool holder keyways are each determined by a standard. For example, ISO 12164-3 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 the functions of both a machining center and a lathe. In this standard, the tolerances of the key and keyway are reduced, integrating the spindle and tool holder and suppressing changes in the phase of the cutting edge of the tool holder.

JP 2004-142053 A Japanese Utility Model Application Publication No. 5-80636

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 cause the tool holder to rotate along with the spindle. Also, even if the spindle servo lock function is turned on, vibrations generated during cutting may cause micro-vibrations in the spindle and tool holder.

The present invention was made to solve the above problems, and its purpose is to provide a fixing mechanism for a stationary tool holder that enables stable heavy cutting.

For this purpose, the 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 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 the manufacturing tolerance of the keyway for the rotating tool holder. In the fixing mechanism for the stationary tool holder that fixes the stationary tool holder to the housing from a direction perpendicular to the axis of rotation, the fixing mechanism includes a first key provided on the end face of the spindle of the machine tool, a first keyway provided on the flange portion of the tool holder fixed to the spindle and engaging with the first key, and a second keyway provided on the flange portion of the tool holder fixed to the spindle. The tool holder has an engagement pin provided on a housing that supports the spindle, and an engagement hole that is provided on the tool holder and engages with the engagement pin, and rotation of the tool holder is suppressed by engagement between the engagement pin and the engagement hole, and the width dimension of the first key is A, the width dimension of the first key groove of the tool holder is B and the tolerance is in the range of b1 to b2, and the width dimension of the key groove of the standardized tool holder is C and the tolerance is in the range of c1 to c2, then the relationship of C≧B>A is established among the width dimensions of the first key, the key groove of the standardized tool holder, and the first key groove of the tool holder, and the tolerance of the key groove of the standardized tool holder and the first key groove of the tool holder is [c2-c1]>[b2-b1].

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

Preferably, the engagement pin includes a tapered shape that narrows toward the axial tip, and the engagement hole includes a tapered hole with the same angle as the tapered shape of the engagement pin.

Preferably, the engagement pin includes a tapered shape that narrows toward the axial tip, is supported so as to be movable in the axial direction 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.

Preferably, the device further includes a determination unit that determines whether the engagement pin and engagement hole are engaged, and a control unit that mechanically controls the rotation of the spindle of the machine tool in response to the determination by the determination unit that the engagement pin and engagement hole are engaged.

Preferably, the tool holder further includes a second key located 180° circumferentially relative to the first key and a second key groove that engages with the second key, and the width dimension and tolerance of the second key are the same as those of a standard tool holder.

Preferably, the length of the second key in the direction of the rotation axis is longer than that of the first key.

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

Preferably, the engagement pin is supported so as to be axially movable via a housing attached to the housing, and the housing is attached to the housing so that its position can be adjusted in the axial direction.

Preferably, the device further includes an alignment mechanism for aligning the center of the engagement pin with the center of the engagement hole.

The present invention makes it possible to perform stable heavy cutting.

FIG. 2 is a front view showing a fixing mechanism of the stationary tool holder according to the first embodiment; FIG. 2 is a front view showing the fixing mechanism for the stationary tool holder according to the first embodiment, illustrating a state in which the tool holder has been removed from the machine tool. FIG. 3 is a bottom view of the spindle end surface as viewed from the arrow III in FIG. 2 . FIG. 4 is a side view of the first key, taken along the arrow IV in FIG. 3 . FIG. 4 is a side view of the second key as viewed from the arrow V in FIG. 3 . FIG. 1 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 in the standard table. FIG. 7 is a plan view of the tool holder as viewed from the arrow VII in FIG. 2 . FIG. 8 is a side view of the first keyway as viewed from the arrow VIII in FIG. 7 . 8 is a side view of the second keyway as viewed from the arrow IX in FIG. 7 . FIG. FIG. 403-1982 shows the MAS BT standard, (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. 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. FIG. 11 is a front view showing a fixing mechanism of a stationary tool holder according to a second embodiment. FIG. 11 is a front view showing a fixing mechanism of a stationary tool holder according to a third embodiment. FIG. 13 is a front view showing a fixing mechanism of a stationary tool holder according to a fourth embodiment. 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 viewed from the arrow XVb in FIG. 15A . FIG. 13 is a front view showing a fixing mechanism of a stationary tool holder according to a sixth embodiment. FIG. 17 is an enlarged view of the circled portion in FIG. 16 . FIG. 23 is a side view of a tool holder body according to a sixth embodiment. FIG. 23 is a perspective view showing a part of an alignment mechanism according to a sixth embodiment.

The embodiment of the present invention will be described in detail with reference to the drawings. Note that the same or corresponding parts in the drawings are given the same reference numerals and their description will not be repeated.

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

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 with the machine tool 1. The fixing mechanism for the stationary tool holder includes a spindle having a pair of keys arranged at 180° symmetrical positions, 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 rotating tool holder, and fixes the stationary tool holder to the housing from a direction perpendicular to the axis of rotation.

The stationary tool attached to the machine tool 1 performs turning on the workpiece 100, which is a workpiece rotating at high speed. Prior to explaining the fixing mechanism of the stationary tool holder, the machine tool 1 and the stationary tool holder 3 will be explained in detail. In the following explanation, the stationary tool holder 3 will be simply referred to as the tool holder 3.

(Regarding 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.

The spindle 11 is provided with a tapered hole 12 along the axis of rotation of the spindle 11. The tapered hole 12 is a hole for mounting the tool holder 3 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 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, for ease of understanding, the key 14 located on the front side is shown with light ink in FIG. 1 and FIG. 2. The keys 14, 15 will be described later.

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 the flange portion 32 of the tool holder 3 described below. This provides a step between the housing 18 and the spindle head 10. The spindle head 10, which rotatably supports the spindle 11, may also be included in the housing.

A case 16 is attached to the lower end of the housing 18. An engagement pin 17 is provided inside the case 16 and is 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.

(About tool holders)
The tool holder 3 is a stationary tool and is used when performing turning on a rotating workpiece 100. As particularly shown in Fig. 2, 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 and clamped by the pull stud 31.

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 grooves 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.

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 from the cutting tip 38. The engagement hole 37 will be described later.

(Regarding the fixing mechanism of the stationary tool holder)
Next, the fixing mechanism of the stationary tool holder will be described in detail with further reference to Figures 3 to 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, keyways 34, 35, engagement pin 17, and engagement hole 37. The keys 14, 15 engage with the keyways 34, 35, and the engagement pin 17 engages with the engagement hole 37.

Before describing the keys 14, 15 and the keyways 34, 35, we will describe the engagement pin 17 and the engagement hole 37. With reference 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 prevents the tool holder 3 from rotating.

The engagement pin 17 is rod-shaped and extends in the left-right direction, and has a flat, angular shape without any rounded corners at its tip. The engagement hole 37 is a recess with a depth that receives 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.

Next, the keys 14 and 15 will be described with further reference to Figures 3 to 6. Figure 3 is a view 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 from the arrow IV in Figure 3 and is a side view showing the first key 14, and Figure 5 is a view from the arrow V in Figure 3 and is a side view showing the second key 15. Figure 6 is a diagram showing JIS standard B6340.

As described above, the keys 14 and 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 opposite each other at positions 180° apart in the circumferential direction.

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. In addition, the length (height) of the first key 14 in the rotation axis direction is D.

The second key 15 shown in FIG. 5 has a tapered shape with its tip narrowing 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 up and down the second key 15. The upper portion 15b of the second key 15 is formed with the same width dimensions and tolerances 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, because 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.

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 higher than the height D of the first key 14.

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

As shown in FIG. 7, the keyways 34, 35 are provided in the flange portion 32 of the tool holder 3 that is fixed to the spindle 11. The keyways 34, 35 are provided at positions 180° apart in the circumferential direction.

As shown in FIG. 8, the first keyway 34 is recessed downward from the upper edge of the flange portion 32. The first keyway 34 is recessed, and its 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.

According to FIG. 10, the width dimension b defined in MAS BT standard 403-1982 is 16.1 mm, with a tolerance ranging from 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 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 keyway 34 is in the range of +0.04 mm to +0.06 mm, i.e., the tolerance b1 is +0.04 mm and the tolerance b2 is +0.06 mm or less.

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 with a wide opening 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 specified 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.

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

Figure 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 Figure 11.

The first key 14 is a standard product according to the above-mentioned JIS standard. In contrast, the first key groove 34 into which the first key 14 engages has a narrower width dimension and a much smaller tolerance than the standard product according to the above-mentioned 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.

The second key 15 is a JIS-compliant product as described above, 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-compliant 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 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.

By narrowing the width dimension of the first keyway 34 and minimizing the tolerance, the gap between the first keyway 34 and the first key 14 can be reduced, making it possible to integrate the machine tool 1 and the tool holder 3. However, if the width dimension of the second keyway 35 as well as the first keyway 34 is narrower than that of the standard product and the tolerance is minimized, alignment becomes difficult and the second key 15 may be difficult to fit into the second keyway 35. Therefore, by making the second keyway 35 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 keyway 35, and the second key 15 is guided to the center of the second keyway 35, so that the first key 14 can be easily engaged with the first keyway 34 with a narrow width dimension and small tolerance.

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 the other key groove smaller than the width dimension and tolerance of the standard product, one key groove (standard product) with the same width dimension and tolerance as the standard product acts as a guide, making it easier to engage the other key groove, which has a narrower width dimension and extremely small tolerance than the standard product. In this way, this embodiment is characterized in that the width dimensions and tolerances of the pair of key grooves are different rather than the same.

Furthermore, the height E of the second key 15 is longer than the height D of the first key 14 by the height E1 of the tapered lower portion 15a. As a result, when attaching the tool holder 3 to the spindle 11, the second key 15 having a guide 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.

From the above, the fixing mechanism of the stationary tool holder in this embodiment can integrate the spindle 11 and the tool holder 3 by engaging the keys 14, 15 with the keyways 34, 35, and can integrate the housing 18 and the tool holder 3 by engaging the engagement pin 17 with the engagement hole 37. This means 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. In addition, the keys 14, 15 and the keyways 34, 35 are engaged in the direction of the rotation axis, while the engagement pin 17 and the engagement hole 37 are engaged in a direction perpendicular to the direction of the rotation axis, so the engagement directions are different. This also strengthens the integration of the machine tool 1 and the tool holder 3.

<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 the fixing mechanism for a stationary tool holder according to the second embodiment. The first embodiment and the second embodiment are different 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.

The tip of the engagement pin 17A in this embodiment is tapered toward the axial tip. 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 to correspond to the tip of the engagement pin 17A.

This results in 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.

<Third embodiment>
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 the 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.

In this embodiment, the engagement pin 17B is provided at a midpoint in the longitudinal direction with a tapered section 20B that tapers toward the axial tip. The tapered section 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 section 20B as the boundary. The tip of the engagement pin 17B is flat like the engagement pin 17 in embodiment 1, and does not have to be tapered like the engagement pin 17A in embodiment 2.

The housing 16B includes a tapered hole 19B with the same angle as the tapered portion 20B of the engagement pin 17B. The tapered hole 19B is provided at a position that abuts the tapered portion 20B when the engagement pin 17B is engaged with the engagement hole 37. Even in this embodiment, the tapered portion 20B of the engagement pin 17B and the tapered hole 19B of the housing 16B are tapered together, further improving rigidity.

<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 the 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.

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

The proximity switch 21C can be provided to prevent the spindle 11 of the machine tool 1 from accidentally rotating during turning. According to this embodiment, in addition to the keys 14, 15 and keyways 34, 35, the engagement pin 17 and the engagement hole 37, the spindle 11 of the machine tool 1 can be electrically controlled to prevent rotation.

<Fifth embodiment>
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.

The housing 16 in the first embodiment described above was fixed so as not to move relative to the housing 18. In contrast, the housing 16D in the present embodiment is attached to the housing 18 via the long holes 40D, the mounting bolts 41D, and the adjustment pins 42D. As shown in FIG. 15(B), the long holes 40D are provided at four corners of the upper surface of the housing 16D and extend in a direction perpendicular to the axis of rotation. As shown in FIG. 15(A), the mounting bolts 41D penetrate the long holes 40D from below to above. The adjustment pins 42D extend in a direction perpendicular to the axis of rotation, 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 that its position can be changed in the left-right direction.

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 cause the cutting tip 38 to move from a predetermined position. This may prevent the workpiece 100 from being turned precisely. Furthermore, there is a risk that a load may be applied to the bearing 13 of the spindle 11.

In this embodiment, therefore, a dial gauge 101D for measuring the position of the cutting tip 38 is placed 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 with the dial gauge 101D. If it is determined that the position is correct, the positions of the casing 16D and the housing 18D are fixed with the adjustment pin 42D.

In this embodiment, the case 16D is attached to the housing 18D via the long hole 40D, the mounting bolt 41D, and the adjustment pin 42D, so that the engagement pin 17 can be prevented from pushing the tool holder 3 more than necessary, which would cause the tool holder 3 to be displaced. This allows for more precise cutting.

<Sixth embodiment>
A fixing mechanism for 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 for 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 the engagement hole, and Fig. 19 is a perspective view showing the alignment mechanism. The second and sixth embodiments are common in that the tips of the engagement pins 17, 17E are tapered, but differ 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.

This embodiment includes an alignment mechanism 60E that aligns 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 Figs. 17 and 19, the alignment mechanism 60E includes a plate-shaped portion 61E and a cylindrical portion 62E that protrudes from the plate-shaped portion 61E toward the tool holder 3. The plate-shaped portion 61E is provided with four long holes 64E and four mounting bolts 65E that pass through the long holes 64E to fix the alignment mechanism 60E to the tool holder body 36E. In Fig. 19, the four long holes 64E extend along the horizontal direction of the plate-shaped portion 61E, but they may extend vertically.

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 center alignment 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 with 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.

As shown in Figures 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 Figure 18, the recess 51E is an area in which the plate-shaped portion 61E of the alignment mechanism 60E is located, and has a rectangular shape that is substantially the same as the shape of 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.

For example, when the tip of the engagement pin 17A is tapered as in the second embodiment, the following concerns arise. Specifically, if the engagement pin 17A is misaligned in the radial or vertical direction with respect to the center of the engagement hole 37A, pushing the tool holder 3 hard when engaging the engagement pin 17A with the engagement hole 37A may cause the tool holder 3 to rotate in the direction of the tapered tip of the engagement pin 17A, which may cause a change in the phase of the tool holder and the spindle.

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, allowing movement in the radial direction or up and down by the amount of the long hole 64E. This allows the center of the engagement pin 17E to align with the center of the engagement hole 37E.

<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, and more stable heavy turning can be performed.

As shown in FIG. 9, the second key groove 35 in the first embodiment has a shape that opens widely at the top, but it 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.

In the above embodiment, the fixing mechanism of the stationary tool holder is provided with two keys and two key grooves, but this configuration is not limited to this. For example, there may be only one key and one key groove, or three or more keys and key grooves, and there is no limit to the number of keys and key grooves.

In the above embodiment, the engagement pin is provided so as to be movable in a direction perpendicular to the axis of rotation of the tool holder 3, but the movement direction is not limited to this, and it may be provided so as to be movable, for example, in the direction of the axis of rotation, that is, so as to be movable in the vertical direction.

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.

The present invention is advantageously used in machine tools that can selectively use stationary and rotating tools.

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 keyway, 35 Second keyway, 37, 37A, 37B, 37E Engagement hole, 40E Alignment mechanism.

Claims (9)

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. 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 relative 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 . The stationary tool holder fixing mechanism according to claim 2, wherein the engagement pin is movable in a direction perpendicular to the rotation axis of the tool holder. 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. 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. 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. the second key includes a tapered tip;
3. 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. 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. The fixing mechanism for a stationary tool holder according to claim 1 or 2, further comprising an alignment mechanism for aligning the center of the engagement pin with the center of the engagement hole.