JP2018167335A - Spindle device and machine tool - Google Patents

Abstract

To provide a spindle device and a machine tool capable of stabilizing a rotation balance of a spindle.SOLUTION: A cross pin 60 of a draw bar 40 is equipped with a first pin 61 and a second pin 62 orthogonal to each other. The first pin 61 is inserted in a pair of long holes provided at positions opposite to each other on a peripheral wall of the spindle 20, and a second pin 62 is inserted in second long holes 32A and 32B provided at positions deviated by 90° in a circumferential direction from the pair of the first long holes. During the rotation of the spindle 20, a gravity center of the draw bar 40 is moved by centrifugal force. If the draw bar 40 tends to fall in a pin direction of the first pin 61, the second pin 62 tries to move in the pin direction of the first pin 61. Since the second long holes 32A and 32B regulate the movement in a width direction of the second pin 62, the movement in the pin direction of the first pin 61 is regulated. Therefore, a spindle device 5 can prevent the draw bar 40 from falling in the pint direction of the first pin 61, and thus can maintain the rotation balance of the spindle 20.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a spindle device and a machine tool.

  The machine tool described in Patent Literature 1 includes a main shaft, a draw bar, a spring, a grip portion, an unclamp operation portion, and the like. The main shaft is formed in a hollow shape. The draw bar is provided in the main shaft so as to be movable in the axial direction. The spring is provided in the main shaft and biases the draw bar in the gripping direction (upward). The gripping part is provided at the lower part of the draw bar and grips the tool holder. The unclamp operation part pushes down the drawbar against the spring force. When the draw bar is pushed down, the gripping part releases the grip of the tool holder. When the drawbar moves upward from the lower position, the gripping part grips the tool holder.

  The unclamp operation unit includes a pin, a lever member, an unclamp cam, a roller, and the like. The pins are provided on the upper part of the draw bar so as to extend on both sides in the direction orthogonal to the axial direction of the draw bar. Both end portions of the pin protrude outward from a pair of long holes provided in the main shaft peripheral wall. The pair of long holes are long in the axial direction of the main shaft and are provided at positions facing each other on the main shaft peripheral wall. The lever member is formed in a substantially L shape, and is supported so as to be rotatable about a spindle provided on the spindle head. The tip of the short end, which is one end of the lever member, is formed in a bifurcated shape in plan view and can come into contact with the pin. The unclamp cam is fixed to the side surface of the other end of the lever member. The roller is fixed to a support member of the Z-axis motor. The support member is fixed to the upright column of the machine tool.

  The roller is slidable relative to the cam surface of the unclamp cam by the raising / lowering operation of the spindle head. The lever member is rotated by the relative sliding of the roller and the unclamp cam. When the lever member pushes down the pin, the draw bar moves downward using the elongated hole as a guide. The gripping part releases the grip of the tool holder. When the lever member rotates in the reverse direction, the pin moves upward by a spring force. The gripping part grips the tool holder.

JP 2009-178895 A

  Since the main shaft structure of the machine tool is a structure in which the draw bar moves in the axial direction within the main shaft, there is a gap between the main shaft and the draw bar. When the main shaft rotates at a high speed, the center of gravity of the draw bar moves in the main shaft. Since both ends of the pin are inserted through the pair of long holes, there is a problem that the draw bar easily falls in the extending direction of the pin.

  An object of the present invention is to provide a spindle device and a machine tool that can stabilize the rotation balance of the spindle.

  The spindle device according to claim 1 is provided in a position where the hollow spindle, a gripping part for gripping a tool attached to the spindle, and a side wall of the spindle are opposed to each other. A pair of first elongated holes extending in parallel to the axial direction, and a rod-shaped draw bar provided in the hollow hole of the main shaft so as to be movable in parallel with the axial direction of the main shaft, and having one end connected to the grip portion And a first pin that is provided on the other end side opposite to the one end of the draw bar, extends to both sides in a direction orthogonal to the length direction of the draw bar, and passes through the pair of first long holes. The spindle is provided in the hollow hole of the spindle, and the drawbar includes a spring that biases the gripping part in a first direction in which the tool is clamped, and is rotatable to a spindle head that rotatably supports the spindle To push the first pin on one end. When the lever member having a portion rotates, the pressing portion presses the first pin, and the pair of first pair of second drawbars in the second direction opposite to the first direction against the biasing force of the spring. In a spindle device of a machine tool that releases gripping of the tool by the gripping portion by moving the elongated hole as a guide, rotation of the spindle relative to the pair of first elongated holes is performed on the side wall of the spindle. A pair of second long holes extending in parallel to the axial direction of the main shaft, and provided on the other end side of the draw bar; A second pin extending on both sides in a direction intersecting with the extending direction of the first pin and passing through the pair of second elongated holes, wherein the first elongated hole is the first pin of the first pin. The movement of the first long hole in the width direction is restricted, and the second long Is characterized by restricting the movement of the to the second pin said second long width direction of the hole of the. Since the draw bar is provided so as to be movable in the axial direction in the hollow hole of the main shaft, there is a gap between the draw bar and the inner peripheral surface of the main shaft. When the spindle rotates, the center of gravity of the drawbar moves due to centrifugal force. The spindle device of the present invention includes a first pin and a second pin extending on both sides in a direction orthogonal to the extending direction of the first pin on the other end side of the draw bar. Further, the main shaft device includes a pair of second long holes through which the second pin is inserted at positions shifted in the circumferential direction around the rotation axis of the main shaft with respect to the pair of first long holes on the side wall of the main shaft. The first long hole regulates movement of the first pin in the width direction of the first pin, and the second long hole regulates movement of the second pin in the width direction of the second long hole. When the drawbar is about to fall in the extending direction of the first pin during rotation of the main shaft, the second elongated hole is the second pin of the second pin that extends in a direction intersecting the extending direction of the first pin. The movement of the long hole in the width direction is restricted. Therefore, the spindle device can prevent the drawbar from falling due to the movement of the center of gravity, so that the rotation balance of the spindle can be maintained. Since the spindle device can maintain the rotation balance of the spindle, it is possible to prevent vibration, noise, and cutting accuracy from being reduced due to the rotation balance being lost. The “tool attached to the spindle” means, for example, a tool holder that holds a tool and that is attached to the spindle.

  The pair of second long holes of the main shaft device according to claim 2 are opposed to each other at positions shifted by 90 ° in the circumferential direction around the rotation axis of the main shaft with respect to the pair of long holes on the side wall of the main shaft. The pair of second pins may extend on both sides in a direction orthogonal to the extending direction of the first pin. If the drawbar is about to fall in the direction of the first pin, the second pin located in the direction orthogonal to the first pin also tries to move in the direction of the first pin. At this time, since the second pin contacts the inner edge portions located on both sides in the width direction of the second long hole, it is possible to reliably prevent the drawbar from falling in the main shaft.

  A machine tool according to a third aspect includes the spindle device according to the first or second aspect. Therefore, the machine tool can obtain the effect of the first or second aspect.

  The inventions of claims 1 and 2 can be arbitrarily combined. For example, not all or a part of claim 1 but also at least one of the configurations of claim 2 may be provided. However, in particular, the configuration of claim 1 may be provided, and at least one of the configuration and combination of claim 2 may be provided. Any constituent elements of claims 1 and 2 may be extracted and combined. The present applicant intends to obtain a patent right for such a configuration.

FIG. 3 is a longitudinal sectional view as seen from the right side of the upper half of the machine tool 1. FIG. The front view of the main axis | shaft apparatus 5. FIG. FIG. 4 is a cross-sectional view taken along the line I-I in FIG. 3. II-II arrow direction sectional drawing shown in FIG.

  An embodiment of the present invention will be described. In the following description, left, right, front, back, and top and bottom indicated by arrows in the figure are used. The left-right direction, the front-rear direction, and the up-down direction of the machine tool 1 are the X-axis direction, the Y-axis direction, and the Z-axis direction of the machine tool 1, respectively.

  The structure of the machine tool 1 will be described with reference to FIG. The machine tool 1 includes a base (not shown), an upright column 2, a spindle head 3, a spindle device 5, a tool changer 8, and the like. The upright column 2 is erected on the upper rear side of the base. The spindle head 3 can be moved up and down in the Z-axis direction along the front surface of the upright column 2. The spindle device 5 is provided inside the spindle head 3 in an upright position. The spindle device 5 rotatably supports the spindle 20. The spindle 20 is mounted with a tool 7 (tool holder 70) at the lower end and is rotated by driving the spindle motor 18. The spindle motor 18 is provided above the spindle head 3. The tool holder 70 attaches and holds the tool 7. The tool changer 8 includes a tool magazine 90 and a plurality of grip arms 91. The substantially disk-shaped tool magazine 90 is fixed to a frame (not shown) provided on the upright column 2 and supported on the front side of the spindle head 3. The plurality of grip arms 91 are provided radially on the outer periphery of the tool magazine 90 so as to be swingable between the spindle head 3 side. The tip of the grip arm 91 detachably holds the tool holder 70. The tool changer 8 swings the grip arm 91 in accordance with the ascending / descending operation of the spindle head 3 in the Z-axis direction, and replaces the tool holder 70 attached to the spindle 20 with a tool holder 70 that holds the next tool.

  The spindle head 3 is moved up and down in the Z-axis direction by a Z-axis moving mechanism provided in front of the upright column 2. The Z-axis moving mechanism includes a pair of Z-axis linear guides (not shown), a Z-axis ball screw 13, and a Z-axis motor (not shown). The Z-axis linear guide extends in the Z-axis direction and guides the spindle head 3 in the Z-axis direction. The Z-axis ball screw 13 is disposed between a pair of Z-axis linear guides and is rotatably supported by an upper bearing portion 14 and a lower bearing portion (not shown). The spindle head 3 includes a nut 16 on the back surface. The nut 16 is screwed into the Z-axis ball screw 13. The Z-axis motor rotates the Z-axis ball screw 13 in the forward and reverse directions. Therefore, the spindle head 3 moves up and down with the nut 16 in the Z-axis direction.

  The structure of the spindle device 5 will be described with reference to FIGS. The spindle device 5 includes a spindle 20, a draw bar 40, a spring 50, a cross pin 60, and the like. As shown in FIG. 4, the main shaft 20 extends in the vertical direction and is formed in a hollow shape. The main shaft 20 includes a tapered hole 21 </ b> A at the lower end 21. The taper mounting portion 72 of the tool holder 70 is mounted in the tapered hole 21A. The upper end portion of the main shaft 20 is connected to the output shaft 18A of the main shaft motor 18 via a coupling 19. The main shaft 20 includes a hollow hole 22 along the axis on the inner side. The hollow hole 22 includes a lower accommodation hole 23, a center accommodation hole 24, and an upper accommodation hole 25 in order from the lower end side to the upper end side. The lower accommodation hole 23 accommodates the clamp mechanism portion 27 (an example of the grip portion of the present invention) inside. The clamp mechanism portion 27 is connected to a lower end portion of the draw bar 40 described later, and detachably holds the pull stud 73 of the tool holder 70 in accordance with the vertical movement of the draw bar 40 (see FIGS. 1 and 4). The central accommodation hole 24 has a diameter that is larger in the radial direction than the lower accommodation hole 23, and accommodates a drawbar body 41, a spring receiving member 52, and a spring 50, which will be described later. The upper accommodation hole 25 accommodates a drawbar extension 42 to be described later.

  The main shaft 20 includes a pair of first long holes 31A and 31B and a pair of second long holes 32A and 32B at the same position in the axial direction on the upper end side of the peripheral wall (see FIGS. 2 and 3). The first long holes 31 </ b> A and 31 </ b> B oppose each other across the axis of the main shaft 20 in the left-right direction of the main shaft device 5. The second long holes 32 </ b> A and 32 </ b> B face each other across the axis of the main shaft 20 in the front-rear direction of the main shaft device 5. That is, the second long holes 32A and 32B are arranged at positions shifted by 90 ° in the circumferential direction around the axis (rotary axis) of the main shaft 20 with respect to the first long holes 31A and 31B. The first long holes 31 </ b> A and 31 </ b> B and the second long holes 32 </ b> A and 32 </ b> B are long holes that extend in parallel to the axial direction of the main shaft 20. The width of each of the first long holes 31A, 31B and the second long holes 32A, 32B (the length in the direction perpendicular to the length direction) is such that the first pin 61 and the second pin 62 of the cross pin 60 described later are moved up and down. It is desirable that the length can be guided in the direction and that the gap between the first pin 61 and the second pin 62 is small. The first long holes 31A and 31B are inserted through both ends of a first pin 61, which will be described later, inward (see FIGS. 2, 3, and 5). The second long holes 32A and 32B are inserted through both ends of a second pin 62, which will be described later, inside (see FIGS. 2, 4, and 5).

  The main shaft 20 includes bearings 34A and 34B, a spacer 35, bearings 36A and 36B, a fixing nut 37, and the like on the outer side of the peripheral wall in order from the lower end side to the upper end side (see FIGS. 2 to 4). The bearings 34A, 34B, 36A, 36B are annular general ball bearings, and hold a plurality of balls between the outer ring and the inner ring so as to allow rolling. As shown in FIGS. 1 and 4, the bearings 34 </ b> A, 34 </ b> B, 36 </ b> A, 36 </ b> B are fixed inside the spindle head 3 and rotatably support the spindle 20. The spacer 35 is formed in a substantially cylindrical shape and is interposed between the bearing 34B and the bearing 36A. The bearing 34 </ b> A is engaged from above with respect to a stepped portion 21 </ b> B formed on the outer peripheral portion of the upper surface of the portion of the lower end portion 21 of the main shaft 20 whose diameter is increased radially outward. The annular fixing nut 37 abuts on the bearing 36B from the upper end side of the main shaft 20, and is fastened to a screw portion (not shown) formed on the outer surface of the peripheral wall of the main shaft 20. The fixing nut 37 presses and fixes the bearings 34 </ b> A and 34 </ b> B, the spacer 35, and the bearings 36 </ b> A and 36 </ b> B against the stepped portion 21 </ b> B of the lower end portion 21 of the main shaft 20.

  As shown in FIG. 4, the draw bar 40 is disposed substantially concentrically in the hollow hole 22 of the main shaft 20, and is provided so as to be movable in the vertical direction. The draw bar 40 includes a draw bar main body 41 and a draw bar extension 42. The drawbar body 41 is accommodated in the central accommodation hole 24 of the hollow hole 22. The lower end portion of the drawbar body 41 is connected to the clamp mechanism portion 27. The drawbar extension 42 is provided at the upper end of the drawbar body 41 and is formed in a substantially cylindrical shape having a diameter longer than the diameter of the drawbar body 41 and extending upward. The drawbar extension 42 includes a shaft fixing hole 45 penetrating in the axial direction. The upper end of the drawbar body 41 is inserted and fixed from below into the shaft fixing hole 45 of the drawbar extension 42.

  The drawbar extension 42 includes pin fixing holes 47 and 48 on the peripheral wall on the upper end side. The pin fixing hole 47 penetrates in the left-right direction perpendicular to the axial direction of the drawbar extension 42 and communicates with the shaft fixing hole 45 inside the drawbar extension 42. The pin fixing hole 48 penetrates in the front-rear direction orthogonal to the axial direction of the draw bar extension 42 and communicates with the shaft fixing hole 45 inside the draw bar extension 42. That is, the pin fixing holes 47 and 48 penetrate in a direction orthogonal to the axial direction of the drawbar extension 42 and are orthogonal to each other at the shaft fixing hole 45. The pin fixing hole 47 inserts a first pin 61 of a cross pin 60 described later. The pin fixing hole 48 inserts a second pin 62 of a cross pin 60 described later.

  The shaft fixing hole 45 forms a screw portion (not shown) on the inner peripheral surface above the portion communicating with the pin fixing holes 47 and 48. The fixing screw 49 is fastened to the shaft fixing hole 45 from above and presses the cross pin 60 downward to fix it to the drawbar extension 42. Therefore, the cross pin 60 is integrated with the drawbar extension 42. The drawbar extension 42 has three grooves extending in the circumferential direction on the outer surface on the lower end side of the peripheral wall, and a resin ring washer 44 is disposed inside each of the three grooves. The ring washer 44 contacts the inner surface of the main shaft 20.

  The drawbar body 41 includes a flange 41A and a spring receiving member 52 on the lower end side. The flange portion 41 </ b> A is formed in a flange shape protruding outward in the radial direction of the drawbar body 41 and is accommodated in the central accommodation hole 24 of the main shaft 20. A gap is formed between the lower surface of the flange portion 41 </ b> A and the upper surface of the step portion 24 </ b> A formed in the lower portion of the central accommodation hole 24. The spring receiving member 52 is formed in a substantially cylindrical shape with a bottom, and the drawbar body 41 is inserted into a hole provided in the bottom with the bottom side facing upward and the opening side facing downward. The bottom lower surface of the spring receiving member 52 is in contact with the upper surface of the collar portion 41 </ b> A of the drawbar body 41. The lower end portion of the spring receiving member 52 is in contact with the upper surface of the stepped portion 24 </ b> A of the central accommodation hole 24. The spring receiving member 52 receives a lower end portion of a spring 50 to be described later housed in the central housing hole 24.

  The spring 50 is a substantially cylindrical coil spring and is accommodated in the central accommodation hole 24 of the main shaft 20. The spring 50 inserts the drawbar body 41 inside. The lower end portion of the spring 50 is in contact with the upper surface of the spring receiving member 52. The upper end portion of the spring 50 is in contact with the lower end portion of the draw bar extension 42. The spring 50 always urges the draw bar 40 upward by urging the draw bar extension 42 upward.

  As shown in FIGS. 2, 3, and 5, the cross pin 60 is formed in a cross shape in plan view, and includes a first pin 61 and a second pin 62 that are orthogonal to each other at the center. In order to insert and fix the cross pin 60 in pin fixing holes 47 and 48 provided in the drawbar extension 42, for example, two short-axis first pins 61A and 61B and one long-axis second pin 62 may be configured. The second pin 62 is inserted into the pin fixing hole 48, and both end portions thereof protrude outward from both end portions of the pin fixing hole 48 (see FIG. 4). Each of the first pins 61A and 61B may be inserted into the pin fixing hole 47 from both sides, and fixed to the outer peripheral surface of the second pin 62 previously inserted into the pin fixing hole 48 with an adhesive or the like. The first pins 61A and 61B protrude outward from both ends of the pin fixing hole 47, respectively. On the contrary, the cross pin 60 may be composed of one long-axis first pin 61 and two short-axis second pins 62. In the present embodiment, for convenience of explanation, the cross pin 60 will be described below as one component in which one first pin 61 and one second pin 62 are connected orthogonally to each other.

  As shown in FIGS. 2 to 5, in the main shaft device 5, both end portions of the first pin 61 are arranged in the axial direction of the drawbar 40 from a pair of first long holes 31 </ b> A and 31 </ b> B provided in the peripheral wall on the upper end side of the main shaft 20. Each extends outward (eg, in the left-right direction) in the orthogonal direction. Both end portions of the second pin 62 are directed outward (for example, the front-rear direction) in a direction orthogonal to the axial direction of the draw bar 40 from a pair of second long holes 32A, 32B provided in the peripheral wall on the upper end side of the main shaft 20. Extend each one. The spring 50 urges the draw bar 40 upward in the hollow hole 22 of the main shaft 20 with a strong spring force. Therefore, both end portions of the first pin 61 are in contact with upper end portions of the pair of first long holes 31A, and both end portions of the second pin 62 are in contact with upper end portions of the pair of second long holes 32A.

  As shown in FIG. 4, the taper mounting portion 72 and the pull stud 73 of the tool holder 70 are inserted into the tapered hole 21 </ b> A of the spindle 20 in the spindle device 5 having the above structure. When the taper mounting portion 72 is mounted in the taper hole 21 </ b> A, the steel ball of the clamp mechanism portion 27 engages with the pull stud 73. The draw bar 40 moves upward from the lower position by the spring force of the spring 50. The steel ball of the clamp mechanism 27 moves to a small diameter hole (not shown) formed above the tapered hole 21 </ b> A while being engaged with the pull stud 73. Therefore, the clamp mechanism 27 holds the pull stud 73. The tool holder 70 is strongly elastically urged upward by the draw bar 40 to be in a clamped state. When the draw bar 40 presses the clamp mechanism portion 27 downward, the steel ball moves from the small diameter hole portion to the tapered hole 21A side. Therefore, the clamp mechanism 27 releases the pull stud 73. The tool holder 70 is in an unclamped state.

  A lever member 80 for operating the unclamping of the spindle device 5 will be described with reference to FIG. The lever member 80 is provided inside the rear upper part of the spindle head 3. The lever member 80 is bent into a substantially L shape and is swingable about a support shaft 81. The support shaft 81 is fixed inside the spindle head 3. The lever member 80 includes a vertical lever 83 and a horizontal lever 82. The vertical lever 83 extends obliquely upward from the support shaft 81 with respect to the upright column 2 side, bends upward at the intermediate portion 85, and further extends upward. The lateral lever 82 extends substantially horizontally from the support shaft 81 toward the spindle device 5 side. The lateral lever 82 includes a pressing portion 82A at the tip, and the pressing portion 82A is formed in a bifurcated shape (not shown) in plan view. The pressing portion 82A is arranged so as to sandwich the main shaft 20. The lower surface of the pressing portion 82 </ b> A can come into contact with both end portions of the first pin 61 from the upper side of the cross pin 60 protruding radially outward from the peripheral wall on the upper end side of the main shaft 20.

  The vertical lever 83 includes an unclamp cam 86 on the back of the upper end. The unclamp cam 86 has a cam surface on the upright column 2 side. The cam surface of the unclamp cam 86 can be brought into contact with and separated from the roller 87 fixed to the upper bearing portion 14. The roller 87 slides on the cam surface of the unclamp cam 86. A tension coil spring (not shown) is elastically provided between the longitudinal lever 83 and the spindle head 3. When the lever member 80 is viewed from the right side, the tension coil spring constantly biases the lever member 80 clockwise. Therefore, the lever member 80 always releases the downward pressing of the first pin 61 by the pressing portion 82A of the lateral lever 82.

  With reference to FIG. 1, the tool change operation | movement by the tool change apparatus 8 is demonstrated. With the taper mounting portion 72 of the tool holder 70 mounted in the taper hole 21A of the main shaft 20, the main shaft head 3 rises from the machining position of the work material toward the ATC origin. The unclamp cam 86 provided on the lever member 80 contacts the roller 87 and slides upward. The roller 87 slides along the cam shape of the cam surface of the unclamp cam 86. When viewed from the right side, the lever member 80 rotates counterclockwise about the support shaft 81. The pressing portion 82A of the lateral lever 82 engages both end portions of the first pin 61 from above and presses the draw bar 40 downward. When the draw bar 40 moves downward, both ends of the first pin 61 move downward using the first long holes 31A and 31B provided in the peripheral wall of the main shaft 20 as a guide. At the same time, both ends of the second pin 62 also move downward while guiding the second long holes 32A and 32B provided in the peripheral wall of the main shaft 20. That is, since the first long holes 31A and 31B and the second long holes 32A and 32B guide the cross pin 60 downward, the draw bar 40 can move downward in a balanced and stable posture. The draw bar 40 pushes down the clamp mechanism portion 27 downward. The clamp mechanism 27 releases the pull stud 73. When the spindle head 3 is further raised, the taper mounting portion 72 of the tool holder 70 is pulled downward from the tapered hole 21A of the spindle 20.

  When the spindle head 3 reaches the ATC origin, the tool magazine 90 rotates around a spindle (not shown), and the tool holder 70 holding the next tool specified by the NC program is indexed to the tool change position. The tool replacement position is the lowest position of the tool magazine 90 and a position facing the lower end portion of the main shaft 20 in the vicinity thereof. The next tool held by the tool holder 70 indexed to the tool change position is located below the spindle head 3 moved to the ATC origin.

  The spindle head 3 starts to descend from the ATC origin. As the spindle head 3 is lowered, the taper mounting portion 72 of the tool holder 70 that holds the next tool is inserted into the tapered hole 21 </ b> A of the spindle 20. With the taper mounting portion 72 inserted into the taper hole 21A, the spindle head 3 is further lowered. An unclamp cam 86 provided on the lever member 80 slides the roller 87 downward. The roller 87 slides along the cam shape of the cam surface of the unclamp cam 86. When viewed from the right side, the lever member 80 rotates clockwise about the support shaft 81. The spring 50 pushes up the draw bar 40. The pressing portion 82 </ b> A of the lateral lever 82 is separated upward from the first pin 61 to release the downward pressing of the draw bar 40. The draw bar 40 releases the downward bias of the clamp mechanism portion 27. The clamp mechanism 27 holds the pull stud 73. The tool change operation is complete.

  The tilt prevention function of the draw bar 40 in the spindle device 5 will be described with reference to FIG. When cutting a workpiece with the tool 7 held by the tool holder 70, the spindle 20 and the draw bar 40 provided therein are rotationally driven by the spindle motor 18 at a speed of, for example, about 16000 to 20000 rpm. Since the draw bar 40 is provided so as to be movable in the vertical direction in the hollow hole 22 of the main shaft 20, a gap is formed between the draw bar 40 and the inner surface of the main shaft 20. For example, a dimensional error in manufacturing, wear due to long-term use, and the like occur in the draw bar 40, so that the center of gravity of the draw bar 40 is not necessarily located on the rotation axis of the draw bar 40. The drawbar 40 has a structure in which the drawbar body 41 and the drawbar extension 42 are connected in the vertical direction. There is a high possibility that it is off. Therefore, when the spindle 20 rotates at high speed, the center of gravity of the draw bar 40 tends to move due to centrifugal force.

  As described above, both end portions of the first pin 61 of the cross pin 60 are inserted into the pair of first long holes 31 </ b> A and 31 </ b> B provided in the peripheral wall of the main shaft 20. If a conventional draw bar having only the first pin 61 has a large gap between the draw bar and the inner surface of the main shaft 20, the draw bar tends to fall in the pin direction (the left-right direction in this embodiment) that is the extending direction of the first pin 61. The draw bar 40 of this embodiment includes a cross pin 60. The second pin 62 of the cross pin 60 extends on both sides in the direction orthogonal to the extending direction of the first pin 61. Both end portions of the second pin 62 are inserted into a pair of second long holes 32A and 32B provided in the peripheral wall of the main shaft 20, respectively. The second long holes 32A and 32B are provided at positions shifted by 90 ° about the rotation axis of the main shaft 20 with respect to the first long holes 31A and 31B. The second long hole 32 </ b> A restricts the second pin 62 from moving in the pin direction of the first pin 61. Therefore, the spindle device 5 can prevent the draw bar 40 from falling in the pin direction of the first pin 61.

  On the contrary, both ends of the second pin 62 of the cross pin 60 provided in the draw bar 40 are inserted into a pair of second long holes 32A and 32B provided in the main shaft 20. If the first pin 61 is not taken into account, it can be said that the draw bar 40 easily falls in the pin direction of the second pin 62. The cross pin 60 of the present embodiment includes a first pin 61 extending on both sides in a direction orthogonal to the extending direction of the second pin 62. Both end portions of the first pin 61 are inserted into a pair of first long holes 31A and 31B provided in the peripheral wall of the main shaft 20, respectively. The first long holes 31A and 31B are provided at positions shifted by 90 ° about the rotation axis of the main shaft 20 with respect to the second long holes 32A and 32B. The first long hole 31 </ b> A restricts the first pin 61 from moving in the pin direction of the second pin 62. Therefore, the spindle device 5 can also prevent the drawbar 40 from falling in the pin direction of the second pin 62.

  As described above, the machine tool 1 according to this embodiment includes the spindle device 5. The main shaft device 5 includes a hollow main shaft 20, a clamp mechanism portion 27, a pair of first long holes 31A and 31B, a pair of second long holes 32A and 32B, a draw bar 40, a spring 50, and a cross pin 60. The clamp mechanism portion 27 is provided in the hollow hole 22 of the main shaft 20, and holds the tool holder 70 attached to the tapered hole 21 </ b> A of the main shaft 20. The pair of first long holes 31 </ b> A and 31 </ b> B are provided at positions facing each other on the side wall of the main shaft 20, and extend parallel to the axial direction of the main shaft 20. The pair of second long holes 32A and 32B are provided on the side wall of the main shaft 20 so as to face each other at positions shifted in the circumferential direction around the rotation axis of the main shaft 20 with respect to the pair of first long holes 31A and 31B. , Extending parallel to the axial direction of the main shaft 20. The rod-shaped draw bar 40 is provided in the hollow hole 22 of the main shaft 20 so as to be movable parallel to the axial direction of the main shaft 20, and the lower end portion is connected to the clamp mechanism portion 27. The cross pin 60 is provided in the draw bar extension 42 of the draw bar 40. The cross pin 60 includes a first pin 61 and a second pin 62. The first pins 61 extend on both sides in the direction orthogonal to the length direction of the draw bar 40 and are inserted through the first long holes 31A and 31B. The second pin 62 extends on both sides in a direction orthogonal to the extending direction of the first pin 61 and passes through the second elongated holes 32A and 32B. The spring 50 is provided in the hollow hole 22 of the main shaft 20 and urges the draw bar 40 in the upward direction in which the clamp mechanism unit 27 holds the tool holder 70. The first long holes 31A and 31B restrict movement of the first pin 61 in the width direction of the first long holes 31A and 31B. The second long holes 32A and 32B restrict the movement of the second pin 62 in the width direction of the second long holes 32A and 32B.

  When the spindle 20 rotates, the center of gravity of the draw bar 40 moves. The first pin 61 of the cross pin 60 of the draw bar 40 is inserted through the first long holes 31A and 31B, and the second pin 62 is inserted through the second long holes 32A and 32B. It tends to fall down in the pin direction (extending direction) or the pin direction (extending direction) of the second pin 62. If the draw bar 40 is about to fall in the pin direction (extending direction) of the first pin 61, the second pin 62 tries to move in the pin direction of the first pin 61. The pin direction of the first pin 61 is parallel to the width direction of the second long holes 32A and 32B. Since the second long holes 32A and 32B restrict the movement of the second pin 62 in the width direction of the second long holes 32A and 32B, the main shaft device 5 has the pin bar direction of the first pin 61 as the draw bar 40 moves in the center of gravity. Can be prevented from falling. For the same reason, it is possible to prevent the second pin 62 from falling in the pin direction. Therefore, the spindle device 5 can maintain the rotational balance of the spindle 20. Since the main shaft device 5 can maintain the rotational balance of the main shaft 20, it is possible to prevent vibration, noise, and reduction in cutting accuracy of the work material due to the loss of the rotational balance.

  Needless to say, the present invention is not limited to the above-described embodiment, and various modifications are possible. In the cross pin 60 of the above embodiment, the second pin 62 is extended to both sides in the direction orthogonal to the extending direction of the first pin 61. That's fine. Accordingly, the pair of second long holes 32A and 32B according to the above embodiment are arranged around the rotation axis of the main shaft 20 with respect to the pair of first long holes 31A and 31B according to the position of the second pin 62. What is necessary is just to provide in the position shifted | deviated to the direction. However, as in the above embodiment, the second pin 62 extends to both sides in the direction orthogonal to the extending direction of the first pin 61, and the second elongated holes 32A, 32B are formed into the first elongated holes 31A, 31B. On the other hand, when the draw bar 40 moves in the up-down direction by providing it at a position shifted by 90 ° in the circumferential direction around the rotation axis of the main shaft 20, the first elongated holes 31A, 31B Since the second long holes 32A and 32B can guide the both ends of the second pin 62 well, the draw bar 40 can move in a vertical direction with a balanced and stable posture.

  The spindle device 5 includes four bearings 34A, 34B, 36A, and 36B, but the number of bearings is not limited to four and can be freely changed. The bearing is not limited to a ball bearing, and various bearings can be applied. The spacer 35 may be omitted. The bearings 34 </ b> A, 34 </ b> B, 36 </ b> A, 36 </ b> B and the spacer 35 are fixed to the main shaft 20 by the fixing nut 37, but may be fixed by another method other than the fixing nut 37.

  Since the cross pin 60 of the above embodiment is inserted and fixed in the pin fixing holes 47 and 48 provided in the drawbar extension 42, the two short-axis first pins 61 </ b> A and 61 </ b> B and one long-axis-shaped pin are used. The second pin 62 is divided into two parts and bonded and fixed in a state of being inserted into the pin fixing holes 47 and 48. For example, the cross pin 60 is formed as one part and the drawbar extension 42 is divided into two parts. It is good also as a structure.

DESCRIPTION OF SYMBOLS 1 Machine tool 3 Spindle head 5 Spindle apparatus 7 Tool 20 Spindle 22 Hollow hole 27 Clamp mechanism part 31A, 31B First long hole 32A, 32B Second long hole 40 Drawbar 50 Spring 61 First pin 62 Second pin 70 Tool holder 80 Lever member 82A Pressing part

Claims (3)

A hollow main shaft, a grip portion that is provided in a hollow hole of the main shaft, grips a tool to be mounted on the main shaft, and a side wall of the main shaft are provided at positions facing each other, and extends parallel to the axial direction of the main shaft. A pair of first elongated holes, a rod-shaped draw bar provided in the hollow hole of the main shaft so as to be movable in parallel with the axial direction of the main shaft, and one end portion of which is connected to the grip portion, and the one end portion of the draw bar A first pin that is provided on the other end side opposite to the side of the draw bar and extends in both directions perpendicular to the length direction of the draw bar, and passes through the pair of first long holes, and in the hollow hole of the main shaft The drawbar includes a spring that biases in the first direction in which the gripping part clamps the tool, and is pivotally supported by a spindle head that rotatably supports the spindle, and has the one end at the end. Lever member having a pressing portion for pressing the first pin By the rotation, the pressing portion presses the first pin, and the pair of first elongated holes are guided in the second direction opposite to the first direction against the urging force of the spring. In the spindle device of the machine tool that releases the gripping of the tool by the gripping part by moving it,
The side walls of the main shaft are provided so as to face each other at positions shifted in the circumferential direction around the rotation axis of the main shaft with respect to the pair of first elongated holes, and parallel to the axial direction of the main shaft A pair of second elongated holes extending;
A second pin provided on the other end side of the draw bar, extending to both sides in a direction intersecting the extending direction of the first pin, and passing through the pair of second elongated holes;
The first long hole regulates movement of the first pin in the width direction of the first long hole,
The spindle device of a machine tool, wherein the second long hole regulates movement of the second pin in the width direction of the second long hole. The pair of second long holes are provided on the side walls of the main shaft so as to face each other at positions shifted by 90 ° in the circumferential direction around the rotation axis of the main shaft with respect to the pair of long holes,
The spindle device for a machine tool according to claim 1, wherein the second pin extends on both sides in a direction orthogonal to the extending direction of the first pin.   A machine tool comprising the spindle device according to claim 1.

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