Machine tool

Abstract

The invention provides a machine tool capable of suppressing rotation around a second axis when rotating around a first axis. The machine tool includes: a rotating portion that rotates about a first axis; a first arm extending from the rotating part; a second arm connected to the first arm and rotating about a second axis intersecting the first axis; a single power source for supplying power to the rotating part and the second arm; and a switching mechanism that switches between a state in which rotation of the second arm is prevented or a state in which rotation of the second arm is permitted.

Description

Technical Field

[0001] The technology relates to a machine tool for processing a workpiece. Background Art

[0002] A machine tool is capable of rotating about a vertically extending C-axis and an A-axis intersecting the C-axis. The machine tool can switch between rotation about the C-axis and rotation about the A-axis by clutch operation. A motor transmits power to only one of the C-axis and the A-axis (see Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-101122 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] Power transmission to the A-axis is performed via multiple gears. There is backlash between the gears. When rotating around the C-axis, there is a concern that the backlash may increase vibration and cause movement around the A-axis.

[0008] The present disclosure has been made in view of the above-described circumstances, and an object of the present disclosure is to provide a machine tool that can suppress rotation about a second axis while rotating about a first axis.

[0009] Technical means to solve the problem

[0010] A machine tool according to one embodiment of the present disclosure includes: a rotating portion that rotates around a first axis; a first arm that extends from the rotating portion; a second arm that is connected to the first arm and rotates around a second axis that intersects the first axis; a single power source that supplies power to the rotating portion and the second arm; and a switching mechanism that switches between a state of preventing the rotation of the second arm and a state of allowing the rotation of the second arm.

[0011] In one embodiment of the present disclosure, for example, when the power source supplies power to the rotating portion rotating about the first axis, the switching mechanism prevents the second arm from rotating about the second axis.

[0012] The switching mechanism of the machine tool according to one embodiment of the present disclosure includes a locked portion attached to the second arm and a locking portion locked to the locked portion.

[0013] In one embodiment of the present disclosure, the locking portion is locked to the locked portion mounted on the second arm to prevent rotation around the second axis.

[0014] In the machine tool according to one embodiment of the present disclosure, one of the engaged portion and the engaging portion has a recessed portion, and the other of the engaged portion and the engaging portion has a projecting portion that is inserted into the recessed portion.

[0015] In one embodiment of the present disclosure, the rotation about the second axis is prevented by inserting the convex portion into the concave portion.

[0016] The clamped portion of a machine tool in one embodiment of the present disclosure has a gear with a plurality of teeth formed on the outer periphery, and the clamping portion has: a swing rod, which is arranged on the outer side of the gear in the radial direction of the gear and can swing around an axis parallel to the axis of the gear; a convex portion, which protrudes from one end of the swing rod and is inserted into a recess formed between the teeth of the gear; and a driving source, which is connected to the other end of the swing rod and supplies power for swinging.

[0017] In one embodiment of the present disclosure, the rotation about the second axis is prevented by inserting the protrusion of the swing lever into the recess between the teeth of the gear.

[0018] The locking portion of the machine tool according to one embodiment of the present disclosure includes a pivot shaft disposed closer to the one end portion than to the longitudinal center of the swing lever, and the swing lever is configured to be swingable about the pivot shaft.

[0019] In one embodiment of the present disclosure, the distance between the driving source and the pivot is made longer than the distance between the convex portion and the pivot, that is, the moment is increased according to the principle of leverage, thereby making it difficult for the convex portion to fall off from the concave portion.

[0020] Effects of the Invention

[0021] In the machine tool according to one embodiment of the present disclosure, for example, when the power source supplies power to the rotating portion rotating about the first axis, the switching mechanism prevents the second arm from rotating about the second axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] [ Figure 1 ] is a three-dimensional diagram of the machine tool.

[0023] [ Figure 2 ] is a simplified three-dimensional diagram of the machine tool inside the cover.

[0024] [ Figure 3 ] is the first longitudinal section of the spindle unit.

[0025] [ Figure 4 ] is the second longitudinal cross-sectional view of the spindle unit.

[0026] [ Figure 5 ] is a sectional perspective view of the spindle unit.

[0027] [ Figure 6 ] is a three-dimensional view of the spindle unit with the first shell omitted.

[0028] [ Figure 7 ] is a partially enlarged three-dimensional view of the tooth clutch, the first engaging part and the second engaging part when the first engaging part is engaged between the upper teeth.

[0029] [ Figure 8 ] is a partially enlarged stereoscopic view of the tooth clutch, the first engaging part and the second engaging part when the second engaging part is engaged between the lower teeth.

[0030] [ Figure 9 ] is a simplified three-dimensional diagram of the second arm.

[0031] [ Figure 10 ] is Figure 4 Line XX is a simplified enlarged cross-sectional view of the switching mechanism for cutting the line.

[0032] [ Figure 11 ] is a simplified enlarged stereoscopic view of the structure near the switching mechanism.

[0033] [ Figure 12 ] is a partial enlarged side view of the gear.

[0034] [ Figure 13 ] is an explanatory diagram illustrating the relationship between the rotation trajectory T of the convex portion around the pivot and the gear.

[0035] [ Figure 14 ] is a reference diagram illustrating the relationship between the rotation trajectory T of the convex portion around the pivot and the gear. DETAILED DESCRIPTION

[0036] Hereinafter, the present invention will be described based on the drawings showing a machine tool according to an embodiment. In the following description, up, down, front, back, left, and right are used as shown in the drawings.

[0037] The machine tool includes a holding table 1. A workpiece is held on the upper surface of the holding table 1. A cover 2 is provided around the holding table 1. The cover 2 is a rectangular parallelepiped extending vertically and includes a front surface 2a, a right surface 2b, a left surface 2c, a rear surface 2d, and an upper surface 2e. An opening and closing door 3 is provided on the front surface 2a, and transparent windows 4 are provided on the right surface 2b and the left surface 2c.

[0038] Three columns 5 extending in the vertical direction are provided on the inner side of the cover 2. The three columns 5 are arranged around the holding platform 1 at a phase interval of approximately 120 degrees when viewed from above. A track 6 is provided on the side of each column 5 on the holding platform 1 side. The track 6 extends in the vertical direction. A moving part 7 and a driving mechanism (not shown) are provided on the track 6, and the moving mechanism includes a ball screw mechanism, etc. A motor 8 that supplies power to the driving mechanism is provided at the upper end of the column 5. Driven by the motor 8, the moving part 7 moves in the vertical direction along the track 6. The motor 8 is provided on the upper surface portion 2e and is located on the outside of the cover 2.

[0039] like Figure 2 As shown, the upper surface portion 2e includes a support plate 2f that is triangular in shape when viewed from above. A motor 10 and a reducer 11 are provided on the support plate 2f. The motor 10 constitutes a single power source. The upper ends of the three columns 5 protrude upward from the upper surface portion 2e. The upper ends are connected to the corners of the support plate 2f via a connecting plate 9. Figure 1 In the figure, description of the upper end portion, the support plate 2f and the connecting plate 9 is omitted.

[0040] A spindle unit 20 is disposed above the holding table 1. The spindle unit 20 is connected to the speed reducer 11 via a vertically extending ball spline 12. The rotation of the motor 10 is decelerated by the speed reducer 11 and then transmitted to the ball spline 12. The ball spline 12 rotates around its axis.

[0041] The spindle unit 20 faces each column 5. The spindle unit 20 and the moving part 7 are connected by two parallel connecting rods 13. The connecting rod 13 is in the shape of a rod. One end of the two connecting rods 13 is connected to the first housing 21 (see FIG. 1 ) of the spindle unit 20 via a rotatable joint 14. Figure 3 The other ends of the two connecting rods 13 are connected to the moving part 7 via a joint 14. The joint 14 is a universal joint or the like. The vertical position of the three moving parts 7 is changed so that the spindle unit 20 moves vertically, forward, backward, left, and right.

[0042] Figure 3 and Figure 4 The cutting position of the cut surface is different. The spindle unit 20 includes a first housing 21 in a truncated cone shape. The first housing 21 constitutes a support portion. The first housing 21 is configured so that the smaller diameter side faces upward and the larger diameter side faces downward. The lower surface of the first housing 21 is entirely open. The connecting rod 13 is connected to the lower edge of the first housing 21.

[0043] A through-hole 21b is formed in the upper surface portion 21a of the first housing 21, extending vertically therethrough. A first rotating shaft 24 is inserted into the through-hole 21b. A sliding bearing 25 is embedded between the first rotating shaft 24 and the through-hole 21b. The sliding bearing 25 rotatably supports the first rotating shaft 24. The first rotating shaft 24 is cylindrical, and wiring 60 is inserted inside the first rotating shaft 24. A plurality of first engaging portions 21c are fixed to the lower side of the upper surface portion 21a of the first housing 21. The plurality of first engaging portions 21c are arranged at approximately equal intervals circumferentially around the through-hole 21b.

[0044] A drive gear 27 is provided approximately midway along the first rotating shaft 24. The drive gear 27 is a two-stage gear consisting of a small-diameter gear 27b and a large-diameter gear 27a. The small-diameter gear 27b is located on the bottom, and the large-diameter gear 27a is located on the top. The first rotating shaft 24 is inserted into the central hole of the drive gear 27. Two bearings 24b, oriented in the vertical direction, are embedded between the first rotating shaft 24 and the drive gear 27. The two bearings 24b are arranged vertically to rotatably support the first rotating shaft 24 and the drive gear 27. The rotation of the ball spline 12 is transmitted to the large-diameter gear 27a.

[0045] The drive gear 27 includes a plurality of second engaging portions 27c. The second engaging portions 27c are fixed to the upper surface of the large-diameter gear 27a and are arranged at approximately equal intervals in the circumferential direction of the first rotating shaft 24. A dog clutch 26 is provided between the upper surface portion 21a of the first housing 21 and the drive gear 27. The dog clutch 26 is cylindrical and short in the axial direction and is arranged with the vertical direction as the axial direction. An annular groove 26a extending in the circumferential direction is formed in the axial center portion of the outer peripheral surface of the dog clutch 26. The dog clutch 26 is made of a thermoplastic resin material, such as a resin material containing polyoxymethylene.

[0046] The dog clutch 26 has a plurality of upwardly projecting upper teeth 26b arranged circumferentially along its upper edge, and a plurality of downwardly projecting lower teeth 26c arranged circumferentially along its lower edge. The dog clutch 26 is positioned outside the first rotating shaft 24. That is, the first rotating shaft 24 is inserted into the inside of the dog clutch 26. A keyway is provided on either the outer circumference of the first rotating shaft 24 or the inner circumference of the dog clutch 26, and a key is provided on the other (both not shown). The axial dimension of the keyway is longer than the key, allowing the key to move vertically along the keyway. The circumferential dimension of the keyway is approximately the same as that of the key. In other words, the dog clutch 26 is circumferentially fixed relative to the first rotating shaft 24 but is axially movable.

[0047] A second housing 22 is provided in the lower opening of the first housing 21. The second housing 22 is cylindrical, hollow inside, and is arranged with the vertical direction as its axial direction. The upper edge of the second housing 22 is positioned inward of the lower edge of the first housing 21. A cross roller bearing 23 is provided between the upper edge of the second housing 22 and the lower edge of the first housing 21. The cross roller bearing 23 rotatably supports the second housing 22. The second housing 22 rotates about the vertical axis.

[0048] A first support tube 22a is formed in the center of the upper surface of the second housing 22. The first support tube 22a extends upward and downward from the upper surface 22d of the second housing 22, penetrating vertically through the upper surface 22d. The lower portion of the first rotating shaft 24 is inserted into the inner side of the first support tube 22a. A keyway is provided on one of the outer circumferential surface of the first rotating shaft 24 and the inner circumferential surface of the first support tube 22a, and a key is provided on the other (both not shown). The axial and circumferential dimensions of the keyway and key are approximately the same, and the keyway and key secure the first support tube 22a to the first rotating shaft 24 in the axial and circumferential directions. The lower end of the first rotating shaft 24 protrudes downward from the first support tube 22a. A cylindrical fixing member 24a is attached to the outer circumference of the lower end of the first rotating shaft 24. The fixing member 24a secures the lower ends of the first support tube 22a and the first rotating shaft 24.

[0049] A second support tube 22b is formed on the upper surface portion 22d of the second housing 22. The second support tube 22b is located radially next to the first support tube 22a. The second support tube 22b protrudes downward from the upper surface portion 22d and is located on the inner side of the second housing 22. The upper end portion of the second support tube 22b is opened and passes through the upper surface portion 22d. The first intermediate shaft 31 is inserted into the second support tube 22b. Two bearings 31a with the vertical direction as the axial direction are provided between the approximately midway portion of the first intermediate shaft 31 and the second support tube 22b. The two bearings 31a are arranged up and down to support the first intermediate shaft 31 in a rotatable manner. The second housing 22, the first rotating shaft 24, the first support tube 22a, and the second support tube 22b constitute a rotating portion.

[0050] The upper end of the first intermediate shaft 31 protrudes upward from the second support cylinder 22b. A spur gear 29, whose axial direction is the vertical direction, is engaged with the upper end. The spur gear 29 meshes with the small-diameter gear 27b of the drive gear 27. The lower end of the first intermediate shaft 31 is located near the lower surface of the second housing 22. A bevel gear 30 is engaged with the lower end.

[0051] A portion of the circumferential surface of the second housing 22 protrudes radially outward and obliquely downward. Hereinafter, this protruding portion is referred to as the protrusion 22c. The lower end of the protrusion 22c is open. The protrusion 22c is located adjacent to the second support tube 22b. The first arm 40 is connected to the lower end of the protrusion 22c. The angle formed between the protrusion 22c and the circumferential surface of the second housing 22 is an acute angle, for example, approximately 30 degrees.

[0052] The first arm 40 includes a bottomed cylindrical housing 41. The opening of the housing 41 is connected to the opening of the protrusion 22c. The housing 41 extends in the same direction as the protrusion of the protrusion 22c. The upper portion of the housing 41 accommodates the second intermediate shaft 32 and two bearings 32a. The second intermediate shaft 32 extends in the same direction as the protrusion. The bearings 32a have the protrusion direction as their axial direction. The two bearings 32a are arranged along the protrusion direction to support the second intermediate shaft 32. A bevel gear 34 is engaged with the upper end of the second intermediate shaft 32. The bevel gear 34 meshes with the bevel gear 30 of the first intermediate shaft 31.

[0053] The third intermediate shaft 33 and two bearings 33a are housed in the center of the housing 41. The third intermediate shaft 33 extends in the same direction as the protruding direction. The bearings 33a have their axial directions oriented in the protruding direction. The two bearings 33a are aligned along the protruding direction and support the third intermediate shaft 33. A coupling 37 connects the upper end of the third intermediate shaft 33 to the lower end of the second intermediate shaft 32. A hypoid pinion 33b is formed at the lower end of the third intermediate shaft 33.

[0054] An opening 42 is formed in the side surface of the lower end of the housing 41. The opening 42 is located on the side of the second housing 22. The second rotating shaft 35 is housed in the lower end of the housing 41. The second rotating shaft 35 extends in a direction perpendicular to the protruding direction (hereinafter referred to as the perpendicular direction) and passes through the lower end of the housing 41. One end of the second rotating shaft 35 protrudes from the opening 42. The second rotating shaft 35 is cylindrical, and the wiring 60 is inserted into the inner side of the second rotating shaft 35.

[0055] The lower end of the housing 41 houses a first bearing 35a, a second bearing 36a, and a hypoid gear 36. The first bearing 35a is located opposite the opening 42 and supports the other end of the second rotating shaft 35. The second bearing 36a is located between the first bearing 35a and the opening 42 and supports the outer circumference of the hypoid gear 36. The second rotating shaft 35 is inserted into the hypoid gear 36, which is fixed to the center of the second rotating shaft 35. The hypoid gear 36 is connected to the second rotating shaft 35 and meshes with the hypoid pinion 33b.

[0056] The reduction ratio of the hypoid gear 36 and the hypoid pinion 33b is higher than the reduction ratio of the two bevel gears 30 and 34, and higher than the reduction ratio of the spur gear 29 and the small-diameter gear 27b. Alternatively, a worm wheel may be used in place of the hypoid gear 36, and a worm gear may be used in place of the hypoid pinion 33b. In such a case, the reduction ratio of the worm wheel and worm gear is higher than the reduction ratio of the two bevel gears 30 and 34, and higher than the reduction ratio of the spur gear 29 and the small-diameter gear 27b.

[0057] A second arm 43 is connected to the periphery of the opening 42. The second arm 43 includes an arm portion 44 and a support tube 45. The arm portion 44 is configured to bend the center of the rod and includes a first portion 44a extending in a direction parallel to the housing 41 and a second portion 44b extending in a direction intersecting the first portion 44a. One end of the first portion 44a is integrally connected to one end of the second portion 44b. The other end of the first portion 44a is cylindrical with its axis oriented in the orthogonal direction and faces the periphery of the opening 42. One end of the second rotating shaft 35 protruding from the opening 42 is fixed to the other end of the first portion 44a.

[0058] A through hole 44c is formed in the second portion 44b, through which the wiring 60 is inserted. A support cylinder 45 is provided at the other end of the second portion 44b. The support cylinder 45 is arranged so that the axis of the support cylinder 45 is aligned with the axis of the first rotating shaft 24. The support cylinder 45 coaxially supports the main shaft 46 on its inner side. A motor is provided in the support cylinder 45. A tool 47 is mounted at the lower end of the main shaft 46. The motor supplies power to the main shaft 46, causing the main shaft 46 and the tool 47 to rotate. The wiring 60 is electrically connected to the motor through the second rotating shaft 35 and the through hole 44c, and is supplied with power.

[0059] like Figure 3 As shown, when the axis of the first rotating shaft 24 is represented by C, the axes of the spindle 46 and the tool 47 are aligned with C. When the axis of the second rotating shaft 35 is represented by A, the tip of the tool 47 is located at A. That is, the tip of the tool 47 is located at the intersection of the axes C and A. The angle θ formed by the axes C and A is approximately 60 degrees. The angle θ can be greater than 45 degrees and less than 90 degrees, preferably greater than 50 degrees and less than 90 degrees, and more preferably greater than 55 degrees and less than 80 degrees.

[0060] Figure 6 This is a perspective view of the spindle unit with the first housing omitted. Figure 7 This is a partially enlarged perspective view of the dog clutch, the first engagement portion, and the second engagement portion when the first engagement portion is engaged between the upper teeth. Figure 8 It is a partially enlarged perspective view of the dog clutch, the first engagement portion, and the second engagement portion when the second engagement portion is engaged between the lower teeth.

[0061] like Figure 7 、 Figure 8 As shown, the first engaging portion 21c includes a fixing portion 21c1 fixed to the upper surface 21a of the first housing 21, and a protrusion 21c2 protruding downward from the fixing portion 21c1. Inclined surfaces are formed on both sides of the lower end of the protrusion 21c2. The width of the lower end of the protrusion 21c2 is smaller than the width between the upper teeth 26c.

[0062] The second engaging portion 27c includes a fixed portion 27c1 fixed to the upper surface of the large-diameter gear 27a, and a protrusion 27c2 protruding upward from the fixed portion 27c1. Inclined surfaces are formed on both sides of the upper end of the protrusion 27c2 so that the width of the protrusion 27c2 in the circumferential direction of the dog clutch 26 decreases as it moves upward. The width of the upper end of the protrusion 27c2 is smaller than the width between the upper teeth 26b.

[0063] The air cylinder 50 is mounted on the outside of the first housing 21. The air cylinder 50 has a rod 50a with an axial direction extending in the vertical direction. The rod 50a protrudes downward from the air cylinder 50 and is moved up and down by air pressure. A forked fork 52 is mounted at the lower end of the rod 50a. The base end of the fork 52 is rotatably connected to the lower end of the rod 50a, with the radial direction of the dog clutch 26 as the rotational axis. The forked portion of the fork 52 engages with the groove 26a. The forked portion of the fork 52 is located inside the first housing 21, while the base end of the fork 52 is located outside the first housing 21.

[0064] A support shaft 51 extending in the radial direction of the dog clutch 26 is provided in the first housing 21. The support shaft 51 passes through a midway portion of a base end portion of the fork 52. The support shaft 51 supports the fork 52 so as to be rotatable about its axis.

[0065] When the rod 50a moves downward, the forked portion of the fork 52 moves upward with the support shaft 51 as a fulcrum, and the first engaging portion 21c engages between the upper teeth 26b of the dog clutch 26 (see FIG. Figure 7 When the rod 50a moves upward, the forked portion of the fork 52 moves downward with the support shaft 51 as a fulcrum, and the second engaging portion 27c engages between the lower teeth 26c of the dog clutch 26 (see Figure 8 ).

[0066] exist Figure 7 In the figure, the first housing 21, cylinder 50, and fork 52 are omitted. When the bifurcated portion of the fork 52 moves upward and the first engaging portion 21c engages between the upper teeth 26b, the dog clutch 26, the first rotating shaft 24, and the second housing 22 are fixed to the first housing 21. The second engaging portion 27c does not engage between the lower teeth 26c of the dog clutch 26.

[0067] The ball spline 12 rotates as the motor 10 rotates, and this rotation is transmitted to the large-diameter gear 27a, causing the drive gear 27 to rotate. The spur gear 29 meshing with the small-diameter gear 27b rotates, causing the first intermediate shaft 31, bevel gear 30, bevel gear 34, second intermediate shaft 32, and third intermediate shaft 33 to rotate. The hypoid pinion 33b at the lower end of the third intermediate shaft 33 rotates, causing the hypoid gear 36 to rotate. The second rotating shaft 35 and the second arm 43 rotate about the axis A along with the hypoid gear 36. Hereinafter, the axis A will also be referred to as the A-axis. The A-axis constitutes the second axis. Furthermore, the dog clutch 26, the first rotating shaft 24, and the second housing 22 are fixed to the first housing 21 and therefore do not rotate.

[0068] exist Figure 8 In the figure, the first housing 21, cylinder 50, and fork 52 are omitted. When the forked portion of the fork 52 moves downward and the second engaging portion 27c engages between the lower teeth 26c, the dog clutch 26, the first rotating shaft 24, and the second housing 22 are connected to the drive gear 27. The rotation of the ball spline 12 is transmitted to the drive gear 27, and the first rotating shaft 24, the second housing 22, the first arm 40, and the second arm 43 rotate about the axis C together with the drive gear 27. Hereinafter, the axis C will also be referred to as the C-axis. The C-axis constitutes the first axis. In addition, because the first intermediate shaft 31, the second intermediate shaft 32, the third intermediate shaft 33, and the second rotating shaft 35 also rotate about the C-axis together with the drive gear 27, the first intermediate shaft 31, the second intermediate shaft 32, the third intermediate shaft 33, and the second rotating shaft 35 themselves do not rotate, and the second arm 43 does not rotate about the A-axis.

[0069] When the rotation about the A-axis is switched to the C-axis, the dog clutch 26 moves downward. When the second engaging portion 27c is not located between the lower teeth 26c, the lower teeth 26c contact the inclined surface of the second engaging portion 27c. The force acting on the inclined surface from the lower teeth 26c causes the drive gear 27 to rotate about the C-axis, and the protrusion 27c2 of the second engaging portion 27c is located between the lower teeth 26c.

[0070] When the rotation about the C-axis is switched to the A-axis, the dog clutch 26 moves upward. When the first engaging portion 21c is not positioned between the upper teeth 26b, the upper teeth 26b contact the inclined surface of the first engaging portion 21c. The force acting on the inclined surface from the upper teeth 26b causes the drive gear 27 to rotate about the C-axis, positioning the protrusion 21c2 of the first engaging portion 21c between the upper teeth 26b.

[0071] The machine tool includes a switching mechanism 70. When the rotation about the A-axis is switched to the rotation about the C-axis, the switching mechanism 70 prevents the second arm 43 from rotating.

[0072] As described above, the second arm 43 includes the arm portion 44. The other end portion of the arm portion 44 is cylindrical and faces the peripheral edge portion of the opening 42. Figure 9 As shown, a gear 43a is formed on the outer peripheral surface of the other end portion of the arm portion 44. The gear 43a is located outside the opening 42 in the orthogonal direction.

[0073] like Figure 10 、 Figure 11 As shown, the switching mechanism 70 includes a gear 43a, a cover 71, a pivot 72, a swing lever 73, a cylinder 74, and a rod 75. The cover 71 is in the shape of a thin, rectangular dish. The cover 71 includes a rectangular base plate 710. A first side surface 71a, a second side surface 71b, and a third side surface 71c are respectively defined on three sides of the base plate 710. The first side surface 71a, the second side surface 71b, and the third side surface 71c are connected at right angles to the three sides. The side opposite the first side surface 71a of the cover 71 is open, and the side opposite the base plate 710 of the cover 71 is open.

[0074] The cover 71 is located between the housing 41 and the second arm 43. The substrate 710 is located closer to the housing 41 than the first side 71a, the second side 71b, and the third side 71c. The first side 71a is located on the upper side. The second side 71b and the third side 71c extend downward from the first side 71a and extend at approximately right angles to the first side 71a. The second side 71b and the third side 71c face each other in a direction parallel to the first side 71a. An opening is formed between the lower ends of the second side 71b and the third side 71c. The substrate 710 is fixed to the housing 41. The housing 41 accommodates the upper portion of the gear 43a. That is, the housing 41 is arranged so that the upper portion of the gear 43a can be inserted into the lower opening of the housing 41 (the opening between the lower ends of the second side 71b and the third side 71c).

[0075] The housing 41 houses the pivot 72 and the swing lever 73. The swing lever 73 is located above the gear 43a within the housing 41. The swing lever 73 extends in the opposing direction (parallel to the first side 71a) between the second side 71b and the third side 71c. The swing lever 73 is L-shaped and includes a first portion 73a extending in the opposing direction, and a second portion 73b extending downward from one end of the first portion 73a and at a right angle to the first portion 73a. The second portion 73b is shorter than the first portion 73a. The second portion 73b is located closer to the second side 71b than the third side 71c. The lower end of the second portion 73b constitutes one end 731 of the swing lever 73. The other end of the first portion 73a constitutes the other end 732 of the swing lever 73.

[0076] The pivot 72 extends perpendicularly to the base plate 710 and is positioned midway along the vertical axis of the second portion 73b. Specifically, the pivot 72 is positioned closer to the one end 731 than to the center of the first portion 73a in the longitudinal direction. The longitudinal direction of the first portion 73a corresponds to the longitudinal direction of the swing lever 73. A protrusion 73c is formed at the lower end of the second portion 73b, or the one end 731. The protrusion 73c protrudes toward the gear 43a. The other end 732 is connected to the rod 75. The distance between the connection point between the rod 75 and the other end 732 and the pivot 72 is longer than the distance between the pivot 72 and the protrusion 73c. ​​Therefore, the torque acting on the protrusion 73c is amplified according to the principle of leverage.

[0077] An air cylinder 74 is provided above the first side surface 71a. A rod 75 extends downward from the air cylinder 74. The rod 75 is inserted into a through-hole extending through the first side surface 71a. Driven by the air cylinder 74, the rod 75 moves up and down. When the rod 75 rises, the protrusion 73c is inserted into the recess between the gears 43a. When the rod 75 descends, the protrusion 73c is disengaged from the recess between the gears 43a.

[0078] When rotating about the C-axis, the machine tool control device inserts the protrusion 73c into the recess between the gears 43a, thereby preventing the second arm 43 from rotating about the A-axis. In other words, the second arm 43 is in a state where its rotation about the A-axis is prevented by the switching mechanism 70. When rotating about the A-axis, the control device disengages the protrusion 73c from the recess between the gears 43a, allowing the second arm 43 to rotate about the A-axis. In other words, the second arm 43 is in a state where its rotation about the A-axis is permitted by the switching mechanism 70.

[0079] like Figure 12 As shown, each tooth of gear 43a includes a first inclined surface 431, a second inclined surface 432, and a top 433. The first inclined surface 431 and the second inclined surface 432 form a valley whose circumferential width gradually narrows toward the radial inside. The radially inner ends of the first inclined surface 431 and the second inclined surface form the bottom of the valley. The radially outer ends of the first inclined surface 431 and the second inclined surface form the top 433. The angle formed by a line L passing through the center of gear 43a (the center of the other end of the cylindrical arm 44) and the bottom of the valley (the radially inner ends of the first inclined surface 431 and the second inclined surface) and the first inclined surface 431 is θ1. The angle formed by line L and the second inclined surface 432 is θ2. θ1 is smaller than θ2.

[0080] Figure 13d represents the distance between the rotation trajectory T of the convex portion 73c about the pivot 72 and the top portion 433. In other words, d represents the distance between the top portion 433, the intersection point P of the tangent line to the top portion 433, and the rotation trajectory T. The gear 43a, the pivot 72, and the swing lever 73 are arranged so that the rotation trajectory T passes through the inside of the valley and intersects the second inclined surface 432.

[0081] Figure 14 This is an explanatory diagram when θ1 and θ2 are equal. Figure 14 d1 represents the distance between the rotation trajectory T of the convex portion 73c around the pivot 72 and the top portion 433. That is, d1 represents the distance between the top portion 433 and the intersection point P1 of the tangent line of the top portion 433 and the rotation trajectory T.

[0082] When d is longer than d1, even if the relative position of the swing lever 73 and the gear 43a deviates, the rotation trajectory T is less likely to interfere with the top portion 433. Specifically, the protrusion 73c is less likely to get caught on the top portion 433 and is easily inserted into the recessed portion of the gear 43a. On the other hand, if the relative position of the swing lever 73 and the gear 43a deviates when d1 is used, the rotation trajectory T is more likely to interfere with the top portion 433. Specifically, the protrusion 73c is more likely to get caught on the top portion 433 and is less likely to be inserted into the recessed portion of the gear 43a.

[0083] That is, by making the angle θ1 between the line L and the first inclined surface 431 smaller than the angle θ2 between the line L and the second inclined surface 432 , the convex portion 73 c can be easily inserted into the concave portion of the gear 43 a .

[0084] In the embodiment, the convex portion 73c can be inserted into the concave portion of the gear 43a to prevent the second arm 43 from rotating about the A-axis. However, the convex portion and concave portion can also be opposite. That is, the convex portion can be provided on the second arm 43, and the concave portion can be provided on the swing lever 73. Alternatively, the second arm 43 can be formed of a magnetic material, and the switching mechanism 70 can use an electromagnet. For example, the control device can energize the electromagnet to fix the second arm 43 by magnetic force, thereby preventing the second arm 43 from rotating about the A-axis.

[0085] In the machine tool of the embodiment, for example, when the motor 10 supplies power to the rotating portion rotating about the C-axis, the switching mechanism 70 blocks the second arm 43 from rotating about the A-axis.

[0086] The protrusion 73c is locked in the recessed portion of the second arm 43 to prevent rotation about the axis A. The protrusion 73c of the swing lever 73 is inserted into the recessed portion of the gear 43a to prevent rotation about the axis A.

[0087] Furthermore, by making the distance between the lever 75 and the pivot 72 longer than the distance between the projection 73 c and the pivot 72 , that is, by increasing the moment based on the principle of leverage, the projection 73 c is less likely to fall off from the recess of the gear 43 a .

[0088] The embodiments disclosed herein should be considered in all respects as illustrative and non-restrictive. The scope of the present invention is intended to include all modifications within the claims and equivalents thereto. The matters described in the various embodiments can be combined with each other. In addition, the independent claims and dependent claims described in the claims can be combined with each other in all combinations regardless of the form of citation. Furthermore, a form of a claim that cites two or more other claims (multiple claim form) is used, but this is not limited to this. It is also possible to record in a form of multiple claims that cite at least one multiple claim (multiple claim citing multiple claims).

[0089] Explanation of Figure Numbers

[0090] 10: Motor (power source)

[0091] 21c: First engaging portion (switching mechanism)

[0092] 22: Second housing (rotating part)

[0093] 22a: First support cylinder (rotating part)

[0094] 22b: Second support cylinder (rotating part)

[0095] 24: First rotation axis (rotating part)

[0096] 26: Tooth clutch (switching mechanism)

[0097] 27: Driving gear (switching mechanism)

[0098] 27b: Small diameter gear (switching mechanism)

[0099] 27c: Second engaging portion (switching mechanism)

[0100] 29: Spur gear (switching mechanism)

[0101] 31: First intermediate shaft (switching mechanism)

[0102] 32: Second intermediate shaft (switching mechanism)

[0103] 33: Third intermediate shaft (switching mechanism)

[0104] 33b: Hypoid pinion (switching mechanism)

[0105] 35: Second rotation axis (switching mechanism)

[0106] 36: Hypoid gear (switching mechanism)

[0107] 40: First Arm

[0108] 43: Second Arm

[0109] 43a: Gear (switching mechanism, recessed portion, locked portion)

[0110] 70: Switching mechanism

[0111] 73: Swinging Rod

[0112] 73c: convex part

[0113] 74: Cylinder (driving source)

[0114] 75: Rod (driving source)

Claims

1. A machine tool comprising: a rotating portion, rotating about a first axis; a first arm extending from the rotating portion; a second arm connected to the first arm and rotating about a second axis intersecting the first axis; a single power source for supplying power to the rotating portion and the second arm; and The switching mechanism switches between a state of preventing the rotation of the second arm and a state of allowing the rotation of the second arm.

2. The machine tool according to claim 1, wherein: The switching mechanism includes a locked portion mounted on the second arm and a locking portion locked to the locked portion.

3. The machine tool according to claim 2, wherein: One of the locked portion and the locking portion has a recessed portion, The other of the locked portion and the locking portion has a convex portion that is inserted into the concave portion.

4. The machine tool according to claim 2, wherein: The locked portion includes a gear having a plurality of teeth formed on the outer periphery. The locking portion has: a swing lever, arranged outside the gear in a radial direction of the gear and capable of swinging around an axis parallel to the axis of the gear; a convex portion protruding from one end portion of the swing lever and inserted into a concave portion formed between the teeth of the gear; as well as The driving source is connected to the other end of the swing rod and supplies power for the swing.

5. The machine tool according to claim 4, wherein: The locking portion includes a pivot arranged closer to the one end portion than the center in the longitudinal direction of the swing lever. The swing lever is configured to be swingable about the pivot shaft.

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