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EP-4137718-B1 - MECHANICAL DEVICE HAVING WORM GEAR MECHANISM

EP4137718B1EP 4137718 B1EP4137718 B1EP 4137718B1EP-4137718-B1

Inventors

  • IKEDA, YOHEI

Dates

Publication Date
20260506
Application Date
20220726

Claims (4)

  1. A mechanical device (1) having a worm gear mechanism (24) including: a worm wheel (25) attached to a rotary shaft (2); and a worm shaft (26) including a worm (26a) in mesh with the worm wheel and provided in an accommodation hole (15) of a frame (10), the worm gear mechanism configured to adjust backlash between the worm and the worm wheel by movement of the worm shaft in an axis line direction, the mechanical device (1) including a position adjusting mechanism (30), characterized in that the position adjusting mechanism (30) comprising: a hollow cylindrical holder (32; 62; 72; 82) screwed into the accommodation hole (15) on one end-side of the accommodation hole, the holder configured to rotatably support the worm shaft (26) via an embedded bearing, the holder configured to cause the movement of the worm shaft in the axis line direction by rotation; an axial force generation part (34) including a screw part (36; 56) and engaged to the holder, the axial force generation part configured to exert an axial force on the holder by a screwing action resulting from rotation of the screw part, the axial force is a force in the axis line direction; and a base part (38; 58) provided to the frame, the base part configured to receive a reactive force acting on the axial force generation part (34) as a result of exerting the axial force to the holder.
  2. The mechanical device according to Claim 1, wherein the position adjusting mechanism (30) is configured so that a screwing direction of the screw part of the axial force generation part coincides with the axis line direction.
  3. The mechanical device according to Claim 2, wherein the position adjusting mechanism (30) is configured so that the holder and the axial force generation part are engaged to each other so that the holder can take an arbitrary position in a direction in which the holder is rotated.
  4. The mechanical device according to Claim 3, wherein the axial force generation part (34) includes: a cylinder member (35; 55; 65) including an engaging surface that is engaged to the holder, the engaging surface intersects the axis line direction, the engaging surface is present in a circumferential direction; and a screw member (36; 56) configured to move the cylinder member in the axis line direction by the screwing action.

Description

TECHNICAL FIELD The present invention relates to a mechanical device having a worm gear mechanism, which includes a worm wheel attached to a rotary shaft and a worm shaft including a worm in mesh with the worm wheel and provided in an accommodation hole of a frame, and the worm gear mechanism is configured to adjust backlash between the worm and the worm wheel by movement of the worm shaft in an axis line direction. BACKGROUND ART Examples of the mechanical device having the worm gear mechanism as described above include a rotation indexing device disclosed in PTL 1, for example. The rotation indexing device includes an index shaft (rotary shaft) rotatably supported in a frame via a bearing, and a worm gear mechanism constituted by a worm wheel attached to the rotary shaft and a worm shaft including a worm in mesh with the worm wheel. Note that, the worm shaft is accommodated in an accommodation hole formed in the frame (more specifically, in a worm bracket forming a part of the frame). Further, the worm shaft is rotatably supported with respect to the frame via a receiving stand (holder) provided in a form of being fitted in the accommodation hole on one end side of the accommodation hole and a bearing embedded in the receiving stand. In addition, PTL 1 discloses that in the rotation indexing device, the worm gear mechanism can be configured so that the worm shaft can be advanced and retreated (slid) in the axis line direction and the backlash between the worm and the worm wheel is adjusted by the advance and retreat. Further, PTL 1 discloses that the worm shaft is advanced and retreated in the axis line direction by advancing and retreating the holder, which supports the worm shaft, in a screw manner with respect to the frame (worm bracket). PTL 2 discloses a speed reducer comprising a worm gear of the type suitable for driving proportioning pumps. PTL 3 relates to journal boxes for centrifugal pumps. PTL 4 relates to a measuring device for the adjustment of the axial position of a toroidal worm and a method of use thereof. CITATION LIST PATENT LITERATURE PTL 1: JPH02-014921Y2PTL 2: US 4 261 218PTL 3: US 1 778 258PTL 4: CN 111 536 915 A In such a rotation indexing device of PTL 1, when the holder is configured to be able to be advanced and retreated in a screw manner with respect to the frame, a configuration is adopted in which a male screw is formed on an outer peripheral surface of the holder, a female screw is formed on an inner peripheral surface on the one end-side of the accommodation hole and the holder is provided in a state of being screwed (screw-fitted) in the accommodation hole. With such a configuration, the rotation of the holder advances and retreats (advanced and retreats in a screw manner) the holder itself in the axis line direction with respect to the frame, whereby the worm shaft is advanced and retreated as described above. In the meantime, the backlash is adjusted by rotating the holder as described above and moving the worm shaft in a direction corresponding to the adjustment. In addition, after the adjustment is completed, it is necessary to fix the holder so as not to be rotatable with respect to the frame so that an amount of the adjusted backlash does not change. Note that, as a mechanism for fixing a rotary body to be rotated such as a holder so as not to be rotatable, a fixing mechanism configured to press a disk-shaped spacer (set piece) against an outer peripheral portion of the rotary body by a screw mechanism using a screw member is generally used well. According to such a fixing mechanism, the rotary body is fixed so as not to be rotatable by a frictional force acting between the set piece subjected to the pressing force by the screw mechanism and the portion of the outer peripheral surface of the rotary body to which the set piece is pressed. However, according to such a fixing mechanism, the frictional force acting on the rotary body as a force for preventing the rotation of the rotary body is applied to only the portion of the outer peripheral surface of the rotary body with which the set piece is in contact, i.e., only a portion of the outer peripheral surface of the rotary body in a circumferential direction. For this reason, when such a fixing mechanism is adopted in the rotation indexing device, there is a problem that the rotation of the holder cannot be securely prevented. More specifically, the rotation indexing device is configured to place thereon a workpiece and is used for machining the workpiece. When machining the workpiece, large vibration acts on the rotary shaft via the workpiece along with the machining. In addition, as the vibration acts on the rotary shaft in this way, the vibration also acts on the holder, which supports the worm shaft via the bearing, via the worm wheel attached to the rotary shaft and the worm shaft in mesh with the worm wheel. When the vibration acts on the holder in this way, a force (rotational force) in a rotation direction o