Mechanical device with worm gear mechanism

Abstract

To provide a configuration capable of more reliably fixing a holder to a frame after backlash adjustment in a mechanical device equipped with a worm gear mechanism including a worm wheel fitted to a rotary shaft, a worm shaft engaged with the worm wheel to be installed in a storage hole of the frame, and the holder which rotatably supports the worm wheel and configured to rotate the holder to move the worm shaft in an axial direction thereof and adjust backlash.SOLUTION: A mechanical device comprises a position adjustment mechanism composed of a holder engaged with a storage hole on one end side of the storage hole, an axial force generation unit that applies an axial force on the holder in an axial direction through a screw operation generated through rotation of a screw, and a base that is provided in a frame and that receives a reactive force applied to the axial force generation unit through the application of the axial force to the holder.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a mechanical device equipped with a worm gear mechanism that includes a worm wheel attached to a rotating shaft, a worm that meshes with the worm wheel, and a worm shaft that is provided in an accommodating hole in a frame, and that is configured so that backlash between the worm and the worm wheel is adjusted by moving the worm shaft in the axial direction. [Background technology]

[0002] An example of a mechanical device equipped with such a worm gear mechanism is the rotary indexing device disclosed in Patent Document 1. The rotary indexing device includes a worm gear mechanism consisting of an index shaft (rotating shaft) rotatably supported within a frame via a bearing, a worm wheel attached to the rotating shaft, and a worm shaft including a worm meshing with the worm wheel. The worm shaft is housed in a housing hole formed within the frame (more specifically, within a worm bracket that forms part of the frame). The worm shaft is rotatably supported relative to the frame via a holder that is fitted into the housing hole at one end thereof and a bearing installed within the holder.

[0003] Patent Document 1 also discloses that in the rotary indexing device, the worm gear mechanism can be configured so that the worm shaft can be moved back and forth (slid) in its axial direction, and the backlash between the worm and the worm wheel can be adjusted by the movement of the worm shaft. Patent Document 1 further discloses that the movement of the worm shaft in the axial direction is achieved by threading a holder that supports the worm shaft back and forth relative to a frame (worm bracket). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Jitsukou 2-14921 Summary of the Invention [Problem to be solved by the invention]

[0005] In the rotation indexing device of Patent Document 1, when the holder is configured to be threadably advanced and retreated relative to the frame, a configuration is adopted in which a male thread is formed on the outer peripheral surface of the holder and a female thread is formed on the inner peripheral surface of the one end of the accommodation hole, and the holder is provided in a state of being screwed (screwed) into the accommodation hole. With such a configuration, the holder itself advances and retreats (screws) in the axial direction relative to the frame as the holder rotates, thereby advancing and retreating the worm shaft as described above.

[0006] As mentioned above, backlash adjustment is performed by rotating the holder and moving the worm shaft in the direction corresponding to the adjustment. After the adjustment is complete, the holder must be fixed to the frame so that it cannot rotate, so that the adjusted amount of backlash does not change.

[0007] A commonly used mechanism for fixing a rotating body such as a holder so that it cannot rotate is a fixing mechanism that uses a screw mechanism that uses a screw member to press a disk-shaped spacer (set piece) against the outer periphery of the rotating body. With such a fixing mechanism, the rotating body is fixed so that it cannot rotate due to the friction force that acts between the set piece that is subjected to the pressing force of the screw mechanism and the part of the outer periphery of the rotating body against which the set piece is pressed.

[0008] However, in the case of such a fixing mechanism, the frictional force acting on the rotating body to prevent the rotation of the rotating body acts only on the portion of the outer circumferential surface of the rotating body where the set piece abuts, i.e., only on a portion of the outer circumferential surface of the rotating body in the circumferential direction. Therefore, if such a fixing mechanism is used in the rotation indexing device, there is a problem in that the rotation of the holder cannot be reliably prevented.

[0009] More specifically, the rotary indexing device is configured to receive a workpiece and is used to machine the workpiece. During machining, large vibrations act on the rotating shaft via the workpiece. As vibrations act on the rotating shaft, they also act on the holder that supports the worm shaft via a bearing, via a worm wheel attached to the rotating shaft and a worm shaft meshing with the worm wheel. When vibrations act on the holder, a force (rotational force) is generated in the holder in the direction of rotation of the holder, and this force acts on the holder. The magnitude of this force depends on the magnitude of the vibration.

[0010] In this case, in a rotation indexing device employing the above-described fixing mechanism, the fixing mechanism can only apply the frictional force, which is the force for preventing the holder from rotating, to a portion of the outer peripheral surface of the holder in the circumferential direction, so when large vibrations such as those that occur during workpiece machining act, the rotational force generated by the vibrations may exceed the frictional force. When the rotational force exceeds the frictional force, the holder rotates, and as a result, the worm shaft moves in the axial direction, changing the amount of adjusted backlash.

[0011] As described above, in the fixing mechanism using the set piece and screw mechanism, depending on the mechanical device used, the rotational force may exceed the frictional force due to vibrations or the like generated in the mechanical device, and the mechanism may be insufficient to prevent the holder from rotating so that the adjusted amount of backlash does not change.

[0012] Therefore, the present invention aims to provide a configuration in a mechanical device equipped with a worm gear mechanism configured to adjust backlash by rotating the holder, which allows the holder to be more securely fixed to the frame after backlash adjustment. [Means for solving the problem]

[0013] The present invention is based on a mechanical device equipped with a worm gear mechanism that includes a worm wheel attached to a rotating shaft, a worm that meshes with the worm wheel, and a worm shaft that is provided in an accommodating hole in a frame, and is configured so that backlash between the worm and the worm wheel is adjusted by moving the worm shaft in the axial direction.

[0014] In addition, the present invention provides a mechanical device equipped with a worm gear mechanism based on the above-mentioned premise, which includes a position adjustment mechanism including a holder that is screwed into the accommodation hole at one end side thereof and rotatably supports the worm shaft, and that moves the worm shaft when rotated; an axial force generating unit that has a screw member and applies an axial force, which is a force in the axial direction, to the holder by the screw action caused by the rotation of the screw member; and a base unit that is provided on a frame and that receives a reaction force acting on the axial force generating unit when the axial force is applied to the holder. The axial force generating portion is composed of a cylinder member having an engagement surface that engages with the holder and that intersects with the axial direction and exists in the circumferential direction, and a screw member that moves the cylinder member in the axial direction by a screw action. It is characterized by the following.

[0015] In a mechanical device including such a worm gear mechanism according to the present invention, the position adjustment mechanism may be configured so that the screw insertion direction of the screw member in the axial force generating portion coincides with the axial direction. Furthermore, the position adjustment mechanism may be configured so that the holder and the axial force generating portion engage with each other in a manner that allows them to take any position in the direction in which the holder is rotated. [Effects of the Invention]

[0016] In a mechanical device equipped with a worm gear mechanism according to the present invention, the position adjustment mechanism is configured so that the axial force is applied by the axial force generating unit to the holder, which is threadedly fitted into the receiving hole of the frame, and the reaction force of the axial force acting on the axial force generating unit is received by a base portion provided on the frame. With this configuration, as a result of the axial force acting on the holder threadedly fitted into the receiving hole of the frame, an axial force acts on the threaded portion between the holder and the frame, and the frictional force generated between the two acts on the holder as a force that prevents rotation of the holder. During this threaded engagement, the holder and the frame are in contact around the entire periphery of the holder, and there are multiple contacting portions in the axial direction, which generates a large overall frictional force, thereby more reliably fixing the holder to the frame.

[0017] In addition, in such a mechanical device of the present invention, Screw material By configuring the position adjustment mechanism so that the screw insertion direction coincides with the axial direction, the holder can be more firmly fixed to the frame.

[0018] More specifically, the axial force generating portion is configured such that the force generated by the screw action acts on the holder in the direction of: Screw material It is also conceivable to configure the screw insertion direction of the holder so that it coincides with, for example, a direction perpendicular to the axial direction (the radial direction of the worm shaft). In this case, an inclined surface is formed at the end of the holder, and the axial force generating unit applies a force in the screw insertion direction to the inclined surface. However, in this configuration, the axial force acting on the holder (the force in the axial direction) is a component force of the force generated by the screw action in the axial force generating unit. In contrast, by configuring the axial force generating unit in the position adjustment mechanism so that the screw insertion direction coincides with the axial direction, all of the force generated by the screw action acts on the holder as the axial force. This makes it possible to further securely fix the holder to the frame, compared to a configuration in which the screw insertion direction coincides with the radial direction.

[0019] Furthermore, in the case where the position adjustment mechanism is configured so that the screw insertion direction coincides with the axial direction as described above, by configuring the position adjustment mechanism so that the holder and the axial force generating part are engaged in a manner that allows them to take any position in the direction in which the holder is rotated (rotational direction), the position of the holder in the rotational direction is not restricted by the position of the axial force generating part, and so backlash can be adjusted more precisely.

[0020] More specifically, the position adjustment mechanism may be configured such that, for example, the engagement between the holder and the axial force generating portion is Screw material However, in this case, the position of the holder in the rotation direction is such that the axial force is generated by the axial force generating portion. Screw material On the other hand, if the position adjustment mechanism is configured so that the holder and the axial force generating unit are engaged in a manner that allows them to take any position in the rotation direction, the position of the holder in the rotation direction will be regulated by the position of the axial force generating unit. Screw material Therefore, with this configuration, when adjusting the backlash, the axial force generating portion Screw material Since the position of the holder in the rotation direction can be set to any position regardless of the position of the holder, the backlash can be adjusted more precisely.

[0021] Furthermore, when the position adjustment mechanism is configured so that the holder and the axial force generating part can be engaged in any position as described above, the axial force generating part can be configured so that a cylinder member that engages with the holder and has an engagement surface that exists circumferentially moves in the axial direction by the screw action, thereby making the engagement between the axial force generating part and the holder stronger and ensuring that the holder remains fixed to the frame.

[0022] More specifically, even if the axial force generating unit is configured to press a set screw threaded into a female threaded hole in the frame (base portion) against the end of the holder, the holder and the axial force generating unit are engaged in a manner that allows them to assume any position as described above. However, in this configuration, the axial force generating unit abuts (engages) with the holder only at the tip surface of the set screw. In contrast, if the axial force generating unit is configured to engage with the holder using a cylinder member having the above-mentioned engagement surface, the axial force generating unit and the holder abut (engage) over a surface extending in the circumferential direction. Therefore, with this configuration, the frictional force generated between the axial force generating unit (cylinder member) and the holder when the axial force generating unit applies the axial force to the holder is much greater than in the case of the set screw described above. This large frictional force strengthens the engagement between the axial force generating unit and the holder, thereby reliably maintaining the holder fixed to the frame. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a side cross-sectional view showing an embodiment of a mechanical device including a worm gear mechanism according to the present invention; [Figure 2] 2 is a cross-sectional plan view taken along line AA in FIG. 1. [Figure 3] FIG. 3 is a partially cross-sectional plan view showing the main part in FIG. 2. [Figure 4] FIG. 10 is a partially sectional plan view showing a main portion of another embodiment of a mechanical device including a worm gear mechanism according to the present invention. [Figure 5] FIG. 10 is a partially sectional plan view showing a main portion of another embodiment of a mechanical device including a worm gear mechanism according to the present invention. [Figure 6] FIG. 10 is a partially sectional plan view showing a main portion of another embodiment of a mechanical device including a worm gear mechanism according to the present invention. [Figure 7] FIG. 10 is a partially sectional plan view showing a main portion of another embodiment of a mechanical device including a worm gear mechanism according to the present invention. [Figure 8] FIG. 10 is a partially sectional plan view showing a main portion of another embodiment of a mechanical device including a worm gear mechanism according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

[0024] An embodiment (example) of a machine equipped with a worm gear mechanism according to the present invention will be described below with reference to Figures 1 to 3. In this example, the machine is a rotary indexing device (so-called rotary table device) that indexes the angular position of a table on which a workpiece is placed around the axis of a rotary shaft that supports the table.

[0025] As shown in the figure, the rotary table device 1 is a so-called horizontal rotary table installed with the axis of the rotary shaft 2 oriented vertically. The rotary table device 1 comprises, as its components, a frame 10 installed on a machine tool or the like, a rotary shaft 2 rotatably supported on the frame 10, and a table 3 attached to one end of the rotary shaft 2. The rotary table device 1 also comprises a drive mechanism 20 that rotationally drives the rotary shaft 2 to index it to a set angular position, and a clamp mechanism 40 that holds (clamps) the rotary shaft 2 at the indexed angular position.

[0026] The frame 10 has an insertion hole 14 formed therein so that the rotary shaft 2 and a worm gear mechanism 24 (described later) of the drive mechanism 20 can be disposed therein. In the illustrated example, the frame 10 is made up of a main body 11, which is the main part of the frame 10 and has a through hole formed therein, a cover 13 fixed to the main body 11 at one end in the penetration direction of the through hole so as to abut against an end face thereof, and a bottom 12 fixed to the main body 11 at the other end in the penetration direction so as to be fitted into the through hole.

[0027] The insertion hole 14 in the frame 10 is formed by a through hole in the main body 11 and through holes formed in the cover 13 and the bottom 12. The insertion hole 14 has an inner diameter large enough to accommodate the rotating shaft 2 at each portion in the penetration direction. The rotating shaft 2 is disposed within the insertion hole 14 and is supported relative to the frame 10 by a bearing 4 interposed between the insertion hole 14 and the main body 11. The through hole in the main body 11 that constitutes part of the insertion hole 14 has an inner diameter large enough to accommodate the worm gear mechanism 24.

[0028] The drive mechanism 20 is made up of a drive motor 21 as a drive source for driving the rotary shaft 2 to rotate, and a worm gear mechanism 24 that transmits the rotation of the output shaft of the drive motor 21 to the rotary shaft 2. The worm gear mechanism 24 is made up of a worm wheel 25 that is attached to the rotary shaft 2 so as not to rotate relative to the rotary shaft 2, and a worm shaft 26 that has a worm 26a that meshes with the worm wheel 25.

[0029] The worm 26a is a so-called double-lead worm in which the lead of the tooth surface is slightly different on the left and right sides, and the tooth thickness dimension gradually increases toward one side in the axial direction of the worm shaft 26. The worm gear mechanism 24 including such a double-lead worm 26a is designed so that the backlash between the worm 26a and the worm wheel 25 can be adjusted by moving the worm shaft 26 in the axial direction.

[0030] The worm shaft 26 is provided in the frame 10 by being accommodated in an accommodation hole 15 formed in the main body 11 of the frame 10 so as to communicate with the insertion hole 14. However, the accommodation hole 15 is formed so that its drilling direction is perpendicular to the penetration direction and it penetrates the main body 11 so as to open on both side surfaces.

[0031] The drive motor 21 is attached to one of the two side surfaces of the main body 11 with its output shaft inserted into the accommodation hole 15. The output shaft of the drive motor 21 is connected to a worm shaft 26 via a gear train 22. In the rotary table device 1, the drive of the drive motor 21 is controlled in accordance with a preset numerical control program, so that the rotary axis 2 (table 3) is indexed to an angular position set in the numerical control program.

[0032] In this embodiment, the clamp mechanism 40 is a so-called disk-type clamp mechanism. More specifically, the clamp mechanism 40 clamps the rotating shaft 2 by clamping a clamp disk 42 fixed to the rotating shaft 2 between a clamp piston 41 and the frame 10 (clamp surface 16) using the pressure of the working fluid.

[0033] As described above, the worm shaft 26 provided in the accommodating hole 15 of the frame 10 is configured to have the worm 26a in the center in the axial direction. The worm shaft 26 is supported on the frame 10 by bearings 27, 28 provided on both sides of the worm 26a. However, at one end of the accommodating hole 15 (the side opposite to the side where the worm shaft 26 is connected to the drive motor 21), a holder 32 is provided within the accommodating hole 15, and the bearing 27 on the one end side is provided inside the holder 32.

[0034] The holder 32 is a hollow cylindrical member and is provided in the accommodation hole 15 with its axis aligned with the drilling direction. The worm shaft 26 is provided in the accommodation hole 15 with its axis aligned with the drilling direction. Therefore, when the worm shaft 26 is provided in the accommodation hole 15, these directions are all the same, and therefore, hereinafter, these directions will all be referred to as the "(said) axial direction."

[0035] The holder 32 is formed so that the outer diameter of the portion closer to one end than the intermediate portion in the axial direction is larger than the outer diameter of the portion closer to the other end, and is formed so that there is a step in the intermediate portion of the outer circumferential surface. That is, the holder 32 is configured so that the portion closer to one end than the intermediate portion is formed as a large-diameter portion 32a, which is the portion with a larger outer diameter, and the other end is formed as a small-diameter portion 32b, which is the portion with a smaller outer diameter. Furthermore, a male thread 32c is formed on the outer circumferential surface of the large-diameter portion 32a of the holder 32.

[0036] The holder 32 is provided at one end of the accommodation hole 15, with the small diameter portion 32b facing the center of the accommodation hole 15, and with male threads 32c formed on the outer peripheral surface of the large diameter portion 32a threadedly engaged with the main body 11 of the frame 10. In the accommodation hole 15 formed in the main body 11, a portion (arrangement portion) 15a where the large diameter portion 32a is expected to be arranged when the holder 32 is provided therein has an inner diameter corresponding to the outer diameter of the large diameter portion 32a, and has a female thread 15b formed on its inner peripheral surface. However, the arrangement portion 15a is formed to be larger than the large diameter portion 32a of the holder 32 in the axial direction.

[0037] Furthermore, at one end of the accommodating hole 15, a portion closer to the center than the arrangement portion 15a has a smaller inner diameter than the arrangement portion 15a, and the inner diameter is sized so that the small diameter portion 32b of the holder 32 can be fitted into it. As a result, the large diameter portion 32a of the holder 32 is screwed into the main body portion 11 (arrangement portion 15a) at one end of the accommodating hole 15, and the small diameter portion 32b is fitted into the accommodating hole 15. Note that the portion (outer portion) 15c of the accommodating hole 15 that is outer than the arrangement portion 15a (opposite the center) is formed so that its inner diameter is even larger than that of the arrangement portion 15a.

[0038] The holder 32 is also formed so that the inner diameter of the large-diameter portion 32a is larger than the inner diameter of the small-diameter portion 32b, and has a step in the middle of the inner circumferential surface. Therefore, the holder 32 has a step surface 32f, which is a surface parallel to the radial direction and faces the large-diameter portion 32a, at the boundary between the large-diameter portion 32a and the small-diameter portion 32b on the inner circumferential surface.

[0039] Two bearings 27 are installed inside holder 32 and positioned within small diameter portion 32b. However, small diameter portion 32b has an annular protrusion 32d formed in approximately the center in the axial direction so as to protrude from the inner circumferential surface. One of the two bearings 27 is positioned so as to abut against protrusion 32d on the large diameter portion 32a side relative to protrusion 32d in the axial direction, and the other is positioned so as to abut against protrusion 32d on the opposite side relative to protrusion 32d.

[0040] The worm shaft 26 is supported by the holder 32 provided as described above, with its shaft portion 26b fitted into the bearings 27a, 27b housed in the holder 32. Of the shaft portions on both sides of the worm 26a, the shaft portion 26b supported by the holder 32 is formed so that the shaft diameter of the portion on the worm 26a side fitted into the bearing 27 is larger than that of the portion fitted into the bearing 27. That is, the shaft portion 26b of the worm shaft 26 is formed so as to have a portion where the shaft diameter is enlarged (enlarged diameter portion) between the portion fitted into the bearing 27 and the portion closer to the worm 26a. When the worm shaft 26 is fitted into the bearing 27 as described above, the other bearing 27b on the worm 26a side abuts against the end face of the enlarged diameter portion.

[0041] Furthermore, a lock nut 29 for fixing the relative positions of the holder 32 (bearings 27a, 27b) and the worm shaft 26 in the axial direction is threaded onto the shaft portion 26b of the worm shaft 26, closer to the end than the portion where the bearing 27 is fitted. More specifically, a male thread is formed on the outer peripheral surface of the shaft portion 26b, at a portion closer to the end than the portion where the bearing 27 is fitted onto the shaft portion 26b. Furthermore, the lock nut 29 is threaded onto the male thread formed on the outer peripheral surface of the end side of the shaft portion 26b. Incidentally, in the illustrated example, an annular member such as a washer is interposed on the shaft portion 26b between the threaded lock nut 29 and one of the bearings 27a (the bearing abutting on the large diameter portion 32a side of the protrusion 32d of the holder 32).

[0042] When the lock nut 29 is tightened, the lock nut 29 applies a force to the first bearing 27a toward the enlarged diameter portion of the worm shaft 26 in the axial direction. This force is then applied to the second bearing 27b via the first bearing 27a and the protrusion 32d of the holder 32, and is received by the end face of the enlarged diameter portion. As a result, the second bearing 27b is sandwiched between the enlarged diameter portion of the worm shaft 26 and the protrusion 32d of the holder 32. Accordingly, the first bearing 27a is sandwiched between the protrusion 32d and the lock nut 29 (the annular member). As a result, the relative positions of the holder 32 and the worm shaft 26 in the axial direction are fixed. However, the two are naturally rotatable relative to each other.

[0043] As described above, the holder 32 is disposed in the accommodating hole 15 while being threadedly engaged with the main body 11 (accommodating hole 15) of the frame 10. Therefore, by rotating the holder 32, the holder 32 is displaced in the axial direction within the accommodating hole 15. Since the relative positions of the holder 32 and the worm shaft 26 in the axial direction are fixed as described above, the worm shaft 26 is also displaced in the axial direction as the holder 32 is displaced as described above. Therefore, with regard to backlash adjustment, which is performed by displacing the worm shaft 26 in the axial direction as described above, the displacement of the worm shaft 26 in the axial direction for the adjustment is performed by rotating the holder 32.

[0044] Furthermore, in the main body 11 (accommodating hole 15) of the frame 10 in which the holder 32 is provided as described above, a lid-like member (lid member) 38 that closes the opening is provided at one end of the accommodating hole 15 in an opening on the other side (the side opposite to the side on which the drive motor 21 is attached) of both side surfaces of the main body 11. The lid member 38 is composed of an insertion portion 38a that is inserted into the accommodating hole 15, and an attachment portion 38b that is used to attach the lid member 38 (insertion portion 38a) to the main body 11 of the frame 10.

[0045] More specifically, the cover member 38 has a hollow cylindrical fitting portion 38a whose outer diameter is approximately the same as the inner diameter of the outer portion 15c of the accommodation hole 15 and whose inner diameter is larger than the inner diameter of the large-diameter portion 32a of the holder 32. The attachment portion 38b is a portion formed in a disk shape and whose outer diameter is larger than the outer diameter of the fitting portion 38a.

[0046] Furthermore, the cover member 38 has a configuration in which the insert-fitting portion 38a and the attachment portion 38b are integrally formed. Specifically, the attachment portion 38b is positioned so as to be continuous with the edge of one end of the insert-fitting portion 38a in the axial direction of the insert-fitting portion 38a, and the insert-fitting portion 38a and the attachment portion 38b are integrated together such that the axis of the insert-fitting portion 38a and the center of the attachment portion 38b coincide with each other when viewed in the axial direction of the insert-fitting portion 38a.

[0047] The cover member 38 is attached to the main body 11 with the insert-fit portion 38a inserted into the outer portion 15c of the accommodating hole 15 and the attachment portion 38b abutting against the other side surface of the main body 11. The attachment is performed by screwing a plurality of screw members inserted into the attachment portion 38b of the cover member 38 in its thickness direction into the main body 11. Incidentally, when the cover member 38 is attached to the main body 11 in this manner, a seal member 38c such as an O-ring is interposed between the outer peripheral surface of the insert-fit portion 38a and the inner peripheral surface of the outer portion 15c of the accommodating hole 15.

[0048] A cylinder member 35 is provided at one end of the receiving hole 15, between the holder 32 and the cover member 38. The cylinder member 35 is a cylindrical member with a bottom, and is composed of a cylindrical portion 35a, which is a cylindrical part, and a base end portion 35c that closes the opening of the cylindrical portion 35a at one end side of the cylindrical portion 35a. A male thread 35b is formed on the outer peripheral surface of the cylindrical portion 35a. Meanwhile, a female thread 32e is formed on the inner peripheral surface of the large-diameter portion 32a of the holder 32.

[0049] The cylinder member 35 is provided with its cylindrical portion 35a facing the holder 32, and with the flank surface of the male thread 35b of the cylindrical portion 35a screwed into the large diameter portion 32a (female thread 32e) of the holder 32. Therefore, the flank surface of the male thread 35b of the cylinder member 35 corresponds to the engagement surface.

[0050] The cylinder member 35 (cylindrical portion 35a) has an outer diameter that allows such a screw-fit state to be achieved in relation to the inner diameter of the large-diameter portion 32a of the holder 32. The outer diameter of the cylinder member 35 is approximately the same as (or slightly smaller than) the inner diameter of the fitting portion 38a of the cover member 38 described above.

[0051] The dimension of the cylinder member 35 in the axial direction is such that, in an attached state in which the cylindrical portion 35a is screwed onto the large-diameter portion 32a of the holder 32, the position of the base end portion 35c in the axial direction at least partially overlaps the position of the fitting portion 38a of the cover member 38. The position of the cylinder member 35 in the axial direction in the attached state is such that a gap exists between the base end portion 35c and the attachment portion 38b of the cover member 38.

[0052] Furthermore, the dimension of the cylinder member 35 in the axial direction is sized to allow for displacement of the holder 32 for the backlash adjustment described above, i.e., to allow for a gap to exist between the tip of the cylindrical portion 35a and the step surface 32f of the holder 32 even when the holder 32 is positioned at the outermost position (closer to the cover member 38) during that displacement. Furthermore, to allow for displacement of the holder 32, the dimension of the cylindrical portion 35a of the cylinder member 35 in the axial direction (thickness of the base end portion 35c) is sized to allow for a gap to exist between the end face of the worm shaft 26 and the base end portion 35c when the holder 32 is positioned at the outermost position, i.e., when the end face of the worm shaft 26 is positioned at the outermost position.

[0053] In the mounted state, the cylinder member 35 is arranged such that the position of the cylindrical portion 35a in the axial direction overlaps the position of the lock nut 29 threaded onto the worm shaft 26. Therefore, the cylindrical portion 35a is formed with an inner diameter larger than the outer diameter of the lock nut 29 so that the lock nut 29 can be positioned inside it.

[0054] Furthermore, a screw member 36 is provided between the cylinder member 35 and the cover member 38 in the attached state, and threads to move the cylinder member 35 in the axial direction. More specifically, the cover member 38 has a screw insertion hole 38d formed in its attachment portion 38b so as to penetrate through the thickness direction thereof, and the screw insertion hole 38d has an inner diameter large enough to allow the screw member 36 to be inserted therethrough. Two screw insertion holes 38d are formed at positions symmetrical with respect to the center of the attachment portion 38b when viewed in the thickness direction of the attachment portion 38b. However, the two screw insertion holes 38d, 38d are formed so as to be located within the range in which the base end 35c of the cylinder member 35 exists when viewed in the axial direction.

[0055] Meanwhile, two female screw holes 35d, 35d into which the two screw members 36, 36 inserted through the screw insertion hole 38d are respectively formed in the cylinder member 35. Each of the female screw holes 35d is formed so as to penetrate through the base end portion 35c of the cylinder member 35 in the thickness direction. The two female screw holes 35d, 35d are formed at positions that allow them to be aligned with the two screw insertion holes 38d, 38d formed in the cover member 38 (mounting portion 38b) when viewed in the axial direction.

[0056] In the attached state, the two screw members 36, 36 are inserted into the respective screw insertion holes 38d in the cover member 38 (mounting portion 38b) and screwed into the respective female screw holes 35d in the cylinder member 35 (base end portion 35c). In this embodiment, the screw members 36 are threaded members such as bolts having heads. A washer 36a is interposed between the head of the screw member 36 and the mounting portion 38b. Furthermore, the length of the screw member 36 (the dimension in the axial direction) is such that, with the head of the screw member 36 abutting against the mounting portion 38b via the washer 36a, the screw member 36 is screwed into most of the female screw holes 35d in the base end portion 35c in the axial direction, but the tip of the screw member 36 does not protrude from the base end portion 35c. Incidentally, the washer 36a is a washer such as a seal washer having a sealing function so that the internal fluid (lubricating oil in this embodiment) does not leak from the screw insertion hole 38d.

[0057] According to the rotary table device 1 configured as described above, in the attached state, when the screw member 36 is rotated in the tightening direction from a state in which its head abuts against the attachment portion 38b of the cover member 38 via the washer 36a, the attachment portion 38b restricts the movement of the screw member 36 in the axial direction toward the cylinder member 35, and therefore, a tensile force acts on the cylinder member 35 toward the cover member 38 (attachment portion 38b) due to the threading action caused by the rotation of the screw member 36. As a result, the cylinder member 35, which is in a state in which the male thread 35b of the cylindrical portion 35a is threadedly engaged with the female thread 32e in the large diameter portion 32a of the holder 32, moves by the amount of the gap (backlash) between the male thread 35b and the female thread 32e.

[0058] This movement presses the male thread 35b against the female thread 32e, causing the tensile force (axial force) in the axial direction to act on the holder 32. Therefore, the combination of the screw member 36, which applies the axial force to the holder 32, and the cylinder member 35 corresponds to the axial force generating unit of the present invention. When the axial force acts on the holder 32 in this manner, the reaction force is received by the cover member 38 (mounting portion 38b), which is attached to the frame 10 (main body portion 11) and against which the head of the screw member 36 abuts. Therefore, the cover member 38 corresponds to the base of the present invention. Since the holder 32 is rotated to move the worm shaft 26 for backlash adjustment, as described below, the combination of the holder 32, the axial force generating unit 34, and the base of the holder 32 corresponds to the position adjusting mechanism of the present invention.

[0059] Furthermore, when the axial force acts on the holder 32 as described above, the male thread 32c of the large diameter portion 32a of the holder 32 is pressed in the direction in which the axial force acts (pulling direction) against the female thread 15b of the accommodation hole 15 (arrangement portion 15a) of the frame 10, with which the male thread 32c is screwed. As a result, a frictional force corresponding to the axial force is generated between the male thread 32c and the female thread 15b, and the frictional force acts on the holder 32 as a force to prevent the holder 32 from rotating.

[0060] As described above, the holder 32 and the accommodating hole 15 are engaged with each other by the male thread 32c and the female thread 15b, and the pressed state is a state in which the two are in contact around the entire circumference of the holder 32 and at multiple locations in the axial direction. As a result, a large frictional force is generated overall between the holder 32 (male thread 32c) and the accommodating hole 15 (female thread 15b), and this large frictional force acts on the holder 32. The application of such a large frictional force makes the holder 32 more firmly fixed to the frame 10.

[0061] Moreover, the axial force generating section 34 of this embodiment is configured so that the screw insertion direction of the screw member 36 coincides with the axial direction. As a result, the tensile force acting on the cylinder member 35 by the screw action of the screw member 36 is a force that acts in the direction that coincides with the axial direction. Therefore, with this configuration, all of the tensile force acts on the holder 32 as the axial force, and the holder 32 is fixed to the frame 10 even more firmly.

[0062] Furthermore, the axial force generating unit 34 (cylinder member 35), which engages with the holder 32 in the axial direction to apply the axial force to the holder 32, is provided in such a manner that the cylinder member 35 is screwed onto the holder 32. This allows the axial force generating unit 34 (cylinder member 35) and the holder 32 to take any relative position (phase) in the direction in which the holder 32 is rotated (rotational direction). Therefore, in this configuration, the phase of the holder 32 is not restricted by the phase of the axial force generating unit 34, allowing for more precise adjustment of backlash.

[0063] Furthermore, because the holder 32 and the cylinder member 35 are engaged in a screwed manner as described above, in this engaged state, a large frictional force acts on the cylinder member 35, similar to the relationship between the holder 32 and the accommodating hole 15 described above. Therefore, the application of such a large frictional force makes the engagement between the cylinder member 35 and the holder 32 stronger, and the state in which the holder 32 is fixed to the frame 10 is reliably maintained.

[0064] To adjust the backlash described above in the rotary table device 1 configured as above, first, the screw members 36 that were tightened to maintain the fixed state of the holder 32 to the frame 10 are loosened as described above, so that the axial force (tensile force) due to the threading action of the screw members 36 is no longer acting on the holder 32. This releases the fixed state of the holder 32 to the frame 10, making the holder 32 rotatable relative to the frame 10. Then, the holder 32 is rotated to move the worm shaft 26 in the axial direction, thereby adjusting the backlash.

[0065] After the backlash adjustment is complete, the screw member 36 that was loosened as described above is retightened, thereby returning the holder 32 to the state where it is rotatably fixed to the frame 10 as described above. By maintaining the fixed state of the holder 32 to the frame 10 in this manner, the amount of backlash that was adjusted remains unchanged (is maintained).

[0066] The above describes one embodiment of a mechanical device equipped with a worm gear mechanism to which the present invention is applied (hereinafter referred to as the "embodiment"). However, the present invention is not limited to the embodiment, and can be embodied in other embodiments (variations) such as those described below.

[0067] (1) Regarding the axial force generating unit, in the above-described embodiment, the axial force generating unit 34 is configured so that the direction in which the axial force acts on the holder 32 is the pulling direction toward the cover member 38. However, in the present invention, the axial force generating unit is not limited to being configured so that the axial force acts in the pulling direction, and may be configured so that the axial force acts in a direction that presses the holder 32 toward the worm 26a (pressing direction).

[0068] Specifically, the configuration shown in Fig. 4 can be considered as an example. The configuration in Fig. 4 is an example in which the holder 32 itself is the same as in the above-described embodiment, and in which the cylinder member is threadedly engaged with the holder 32 as in the above-described embodiment, the screw member is a set screw rather than a bolt as in the above-described embodiment. However, in this example, the cylinder member 55 does not have a female threaded hole at the base end 55c as in the above-described embodiment, and the hole formed in the attachment portion 58b of the cover member 58 is a female threaded hole 58d rather than a simple hole as in the above-described embodiment.

[0069] Two female screw holes 58d are formed in the cover member 58, and the set screws 56 are threaded into the respective female screw holes 58d and are provided so as to protrude from the mounting portion 58b towards the cylinder member 55. The two set screws 56, 56 are basically provided so that their tips abut against the base end portion 55c of the cylinder member 55.

[0070] According to this configuration, by tightening the setscrew 56 while it is in contact with the cylinder member 55 (base end 55c), the setscrew 56 receives a reaction force at the portion where it is threaded with the cover member 58 (mounting portion 58b), and applies a force (pressing force) in the pressing direction to the cylinder member 55. As a result, the pressing force acts on the holder 32 as the axial force, and as a result, the holder 32 is fixed to the frame 10 by the frictional force generated between the holder 32 and the frame 10 (accommodating hole 15), as in the previous embodiment. Therefore, in this example as well, the cover member 58 corresponds to the base portion, and the combination of the setscrew 56 and the cylinder member 55 corresponds to the axial force generating portion.

[0071] In this example, the direction of the axial force acting on the holder 32 is opposite to that in the above-described embodiment. As a result, the male thread 55b of the cylinder member 55 is pressed against and engaged with the female thread 32e of the holder 32 at a flank surface facing opposite to that in the above-described embodiment. Therefore, in this example, the engaging surface of the cylinder member 55 is the flank surface of the male thread 55b facing opposite to that in the above-described embodiment.

[0072] (2) In the example described above, the axial force generating unit engages with the holder 32 in such a manner that the axial force generating unit includes a cylinder member and the cylinder member is screwed onto the holder 32, thereby engaging the two so that the cylinder member can apply the axial force to the holder 32. However, in the present invention, even when the axial force generating unit includes a cylinder member, the configuration for engaging the holder and the cylinder member is not limited to the above-described configuration in which the two are screwed onto each other.

[0073] Specifically, the configuration shown in Fig. 5 can be considered as an example. In the configuration of Fig. 5, the cover member 38 and the screw member 36 are the same as those in the above-described embodiment, and the tensile force is applied to the cylinder member by the threading action of the screw member 36, as in the above-described embodiment. However, in this example, the cylinder member 65 does not have a male thread formed on its cylindrical portion 65a, and is configured so that the cylindrical portion 65a has a flange-like portion (enlarged diameter portion) 65e at its tip end (the end on the holder 62 side) that is formed to expand the outer diameter.

[0074] Furthermore, no female thread is formed on the inner peripheral surface of the large diameter portion 62a of the holder 62, and a (donut-shaped) disk-shaped member (disk portion) 62g having a through hole is attached to the end surface of the large diameter portion 62a. The inner diameter of the through hole in the disk portion 62g is slightly larger than the outer diameter of the cylindrical portion 65a of the cylinder member 65 and smaller than the outer diameter of the expanded diameter portion 65e.

[0075] Furthermore, the arrangement of the cylinder member 65 in the axial direction relative to the holder 62 is such that the expanded diameter portion 65e is located closer to the small diameter portion 62b of the holder 62 than the disk portion 62g. As a result, an end face 65e1 of the expanded diameter portion 65e of the cylinder member 65 facing the cylindrical portion 65a and an end face 62g1 of the disk portion 62g of the holder 62 facing the small diameter portion 62b are opposed to each other in the axial direction. Furthermore, the cylinder member 65 is basically arranged in a position such that its end face 65e1 abuts against the end face 62g1 of the holder 62 in the axial direction.

[0076] According to this configuration, when the tensile force acts on the cylinder member 65 due to the threading action of the screw member 36, the axial force in the tensile direction acts on the end face 62g1 of the holder 62 with which the end face 65e1 of the cylinder member 65 abuts as described above. Therefore, in this example, the end face 65e1 serves as the engagement surface of the cylinder member 65. With this configuration, the axial force acts on the holder 62 in this manner, and as a result, the same effect as in the above-described embodiment can be obtained.

[0077] In the configuration in which the holder and the cylinder member are engaged at end surfaces facing each other in the axial direction as described above, the axial force acts in the pulling direction in the example of Fig. 5, but it is also possible to configure the axial force to act in the pressing direction. Specifically, as in the example of Fig. 5, the cylinder member is configured to have an enlarged diameter portion and the holder has a disk portion, and the cylinder member is positioned so that its enlarged diameter portion is closer to the cover member than the disk portion of the holder and abuts against the disk portion. Then, by configuring the pressing force to act on the cylinder member using a mechanism using a press screw as shown in Fig. 4, the axial force in the pressing direction can be applied to the holder.

[0078] (3) In the examples described above, the axial force generating unit includes a cylinder member that applies the axial force to the holder. However, the axial force generating unit of the present invention is not limited to a unit that includes such a cylinder member.

[0079] Specifically, the configuration shown in Fig. 6 can be considered as an example. In the configuration shown in Fig. 6, the cover member 38 is the same as in the above-described embodiment, and the holder 72 is threadedly fitted into the receiving hole 15 as in the above-described embodiment. However, no cylinder member is provided, and the screw member 36 inserted through the cover member 38 is directly threaded into the holder 72. Therefore, the holder 72 is formed to have two female threaded holes 72g, 72g that open at the end face of the large diameter portion 72a and into which the screw member 36 is threaded, and the axial force generating portion is formed only by the two screw members 36, 36 that are threaded into the female threaded holes 72g, 72g. In this configuration, when the screw member 36 is tightened, the axial force in the tensile direction acts on the holder 72, and as a result, the same effect as in the above-described embodiment can be obtained.

[0080] In the configuration without a cylinder member as described above, the axial force generating unit in the example of FIG. 6 is configured so that the axial force acts on the holder in the pulling direction. However, as shown in FIG. 7, for example, the axial force generating unit can be configured so that the axial force acts in the pressing direction. In the example of FIG. 7, the holder 82 is formed so that a flange-shaped portion (flange portion) 82g having an enlarged outer diameter is formed at the end of the large-diameter portion 82a opposite the worm 26a side. The outer diameter of the flange portion 82g is approximately the same as the inner diameter of the outer portion 15c of the accommodating hole 15. Two screw insertion holes 82h, 82h are formed in the flange portion 82g, penetrating the flange portion 82g in the thickness direction and through which the screw member 36 is inserted. The holder 82 is installed in the accommodating hole 15 with the flange portion 82g positioned within the outer portion 15c in the axial direction and loosely fitted into the outer portion 15c.

[0081] Meanwhile, the main body 11 of the frame 10 has two female screw holes 11a, 11a that open to an end surface facing outward in the outer portion 15c of the accommodation hole 15 and into which the screw members 36 are screwed. Furthermore, the two screw members 36, 36 are inserted into the respective screw insertion holes 82h in the flange portion 82g of the holder 82 and are screwed into the respective female screw holes 11a in the frame 10 (main body 11).

[0082] According to this configuration, when the screw member 36 is tightened with its head abutting against the holder 82 (flange portion 82g), the axial force acts on the holder 82 in the pressing direction, resulting in the same effect as the example shown in FIG. 4 . In this configuration, the reaction force generated when the screw member 36 applies the axial force to the holder 82 is received by the portion of the main body 11 (female screw holes 11a) where the screw member 36 is threaded. Therefore, in this example, the portion of the main body 11 of the frame 10 where the female screw holes 11a are formed corresponds to the base. In this example, the cover member 88 is attached to the end face of the holder 82 so as to close the opening. The opening of the accommodation hole 15 is thereby closed by the flange portion 82g of the holder 82 and the cover member 88.

[0083] However, in the case of a configuration without a cylinder member, such as the examples in FIGS. 6 and 7, the position (rotational position) of the holder in the rotation direction, which is changed (positioned) when the holder is rotated for backlash adjustment, is limited by the positions of the screw member and the female screw hole into which the screw member is threaded. That is, in the examples in FIGS. 6 and 7, the rotational position can be changed in increments of an angular range of 180°. Note that, although the limited angular range can be narrowed by increasing the number of female screw holes or screw insertion holes, the limitation remains. In contrast, in a configuration with a cylinder member, such as the above-described embodiment, the holder can assume any position without being limited by the rotational position. Therefore, when more precise backlash adjustment is required, a configuration with a cylinder member is preferable.

[0084] (4) In the examples described above, the axial force generating unit is configured so that the screw insertion direction of the screw member coincides with the axial direction. However, in the present invention, the axial force generating unit is not limited to being configured in this way, Screw material The screw insertion direction may be configured to coincide with the radial direction of the holder.

[0085] Specifically, the configuration shown in Fig. 8 can be considered as an example. In the configuration of Fig. 8, similar to the example of Fig. 6 etc., a cylinder member is not provided, and the holder 92 is configured to have a tapered inclined portion 92i on the lid member 98 side of a large diameter portion 92a where the male thread is formed. Furthermore, the portion disposed in the accommodating hole 17 is formed as an outer disposed portion 17b with a slightly larger diameter than the female thread portion 17a on the lid member 98 side of the female thread portion 17a where the female thread is formed. The holder 92 is disposed such that the inclined portion 92i overlaps with the outer disposed portion 17b in the portion disposed in the accommodating hole 17 in the axial direction.

[0086] Furthermore, the main body 11 of the frame 10 is formed with a through hole 17c drilled in the radial direction so as to open onto the inner circumferential surface of the outer arrangement portion 17b of the accommodation hole 17. The through hole 17c is a female screw hole with a female screw formed on its inner circumferential surface. In addition, the female screw hole 17c has Screw material A set screw 96 is screwed into the holder 92 (inclined portion 92i) as a set screw. Furthermore, a pressing member 95f is interposed between the set screw 96 and the holder 92 (inclined portion 92i) to apply the radial force generated by the screw action of the set screw 96 to the holder 92. The pressing member 95f is a cylindrical member, and is formed so that the end on the holder 92 side is hemispherical.

[0087] According to this configuration, when the setscrew 96 is tightened while the pressing member 95f is in contact with the inclined portion 92i of the holder 92, the pressing member 95f, which is interposed between the setscrew 96 and the holder 92, applies the radial force to the holder 92 due to the screw action. As a result of the radial force being received by the inclined portion 92i of the holder 92, a component force in the pressing direction acts on the holder 92, and this component force becomes the axial force in the pressing direction. Note that, with this configuration, the reaction force generated when the pressing member 95f applies the axial force to the holder 92 is received by the threaded portion of the main body 11 (the externally threaded hole 17c) into which the setscrew 96 is threaded. Therefore, in this example, the portion of the main body 11 of the frame 10 where the internally threaded hole 17c is formed corresponds to the base portion.

[0088] (5) In the above-described examples of machinery equipped with a worm gear mechanism to which the present invention is applied, the present invention is applied to a so-called horizontally-mounted rotary table device in which the axis of the rotary shaft is oriented vertically. However, machinery to which the present invention is applied is not limited to such rotary table devices.

[0089] For example, as a machine tool-related machine device equipped with a worm gear mechanism configured to adjust backlash by moving a worm shaft in its axial direction, as is the premise of the present invention, there is a so-called cradle-type tilting table device that includes a tilting table (cradle) made up of a table on which a workpiece is placed and a pair of arms that support the table, with the axis of the arms (rotation shaft) separated from the mounting surface of the table on which the workpiece is placed. Therefore, the present invention can also be applied to such a tilting table device.

[0090] Furthermore, the mechanical devices to which the present invention is applicable are not limited to the circular table device and tilting table device described above, but may be other machine tool related mechanical devices as long as they are equipped with a worm gear mechanism configured as described above, and furthermore, the present invention is not limited to machine tool related mechanical devices but may be other mechanical devices.

[0091] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0092] 1 Rotating table device (mechanical device) 2 rotation axes 3 tables 4 Bearings 10 frames 11 Main body 12 Bottom 13 Cover 14 Insertion hole 15 Receiving hole 15a Placement part 15b female thread 15c outer part 16 Clamping surface 20 Drive mechanism 21 Drive motor 22 Gear train 24 Worm gear mechanism 25 worm wheel 26 Worm shaft 26a Warm 26b Shaft 27 Bearings 29 Lock nut 30 Position adjustment mechanism 32 Holder 32a Large diameter section 32b Small diameter section 32c male thread 32d protrusion 32e female thread 32f Stepped surface 34 Axial force generating section 35 Cylinder parts 35a Cylindrical part 35b male thread 35c proximal end 35d female screw hole 36 Screw member 36a washer 38 Lid member (base part) 38a Insert part 38b Mounting part 38c Sealing material 38d Screw insertion hole 40 Clamping mechanism 41 Clamp piston 42 Clamp disc 55 Cylinder parts 55b male thread 55c proximal end 56 Set screw (screw component) 58 Lid member (base part) 58b Mounting part 58d female screw hole 62 Holder 62a Large diameter section 62b Small diameter section 62g disc part 62g1 End surface facing the small diameter part 65 Cylinder parts 65a Cylindrical part 65e Expanded section 65e1 End surface facing the cylindrical portion (engagement surface) 72 Holder 72a Large diameter section 72g female screw hole 11a female screw hole 82 Holder 82a Large diameter section 82g flange 82h Screw insertion hole 88 Lid member 17 Receiving hole 17a Female thread 17b Outside placement part 17c female screw hole 92 Holder 92a Large diameter section 92i Slope 95f Pressing member 96 Set screw (screw component) 98 Lid member

Claims

1. A worm wheel attached to a rotating shaft and a worm gear meshing with the worm wheel. The worm shaft is provided in the receiving hole of the frame, and the worm shaft is provided in the receiving hole of the frame. The backlash between the worm and the worm wheel is adjusted by the movement of the worm shaft. A mechanical device having a worm gear mechanism configured to be adjusted, The worm shaft is threadedly engaged with the receiving hole at one end thereof and is rotatable. A holder that supports the worm shaft and rotates to cause the worm shaft to move. a position adjusting mechanism including an axial force generating unit having a screw member provided so that its axis is located at a position different from the axis of the holder as viewed in the axial direction and applying an axial force, which is a force in the axial direction, to the holder by a screw action caused by rotation of the screw member; and a base unit provided on the frame and receiving a reaction force acting on the axial force generating unit by applying the axial force to the holder, The axial force generating portion includes a cylinder member having an engagement surface that engages with the holder, the engagement surface intersecting the axial direction and existing over a circumferential direction, and the screw member is provided to apply the axial force to the cylinder member. A mechanical device equipped with a worm gear mechanism.

2. The position adjustment mechanism is configured so that the screw insertion direction of the screw member in the axial force generating portion coincides with the axial direction. A mechanical device comprising the worm gear mechanism according to claim 1.

3. The position adjustment mechanism is configured so that the holder and the axial force generating unit can be engaged in any position in the direction in which the holder is rotated. A mechanical device comprising the worm gear mechanism according to claim 2.

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