Robot arm assembly

A robot arm assembly with tubes or pipes carrying fluids or electrical cables which do not get bent and are relatively straight, and are not disrupted by, the moving parts of the robot arm includes a first robot arm, a second robot arm, a third robot arm, and a flexible carrying tube. The second robot arm includes a first axle base, a first input shaft, a first bevel gear, and a second bevel gear. The flexible tube is inserted into the first bevel gear and the second bevel gear along a first axis, and fixed to the output shaft.

BACKGROUND

1. Technical Field

The present disclosure relates to robot arm assemblies, particularly to a robot arm assembly including several robot arms rotatably connected.

2. Description of Related Art

Robots are applied to perform tasks in environments hazardous or difficult for human operators, such as to spray or clean a workpiece, for example. Tubes or cables are provided to transfer liquid for spraying or cleaning in robots, in spraying or cleaning process. In order to maintain an orderly appearance, the cables are received in a tube which is placed inside the robot and pass through a plurality of arms of the robot. However, because the arms of the robot rotate along different axes, the tubes for receiving the cables are bent following an operation of the robot. The flow of liquid in the cable may be disrupted, which results in a lower spraying efficiency or cleaning efficiency. In addition, action of the arms may abrade or even sever the tube.

Therefore, there is room for improvement in the art.

DETAILED DESCRIPTION

FIGS. 1 and 2show one embodiment of a robot arm assembly100. The robot arm assembly100includes a first robot arm10, a second robot arm30, a third robot arm50, and a flexible cable receiving tube70. The first robot arm10is sleeved on the second robot arm30, and is rotatably connected to the second robot arm30. The second robot arm30is sleeved on the third robot arm50, and is rotatably connected to the third robot arm50. The flexible cable receiving tube70is inserted into the second robot arm30and the third robot arm50, and an end of the flexible cable receiving tube70is connected to an end of the third robot arm50away from the first robot arm10. In the illustrated embodiment, the robot arm assembly100is configured for a six-axis robot. The first robot arm10, the second robot arm30, and the third robot arm50are a fourth robot arm (not shown), a fifth robot arm (not shown), and a sixth robot arm (not shown) of a six-axis robot, respectively.

The first robot arm10is substantially cylindrical, and rotates around a first axis A (shown inFIG. 2). The second robot arm30includes a first input shaft31, a first axle base33, a first bevel gear35, a first bearing36, a second bevel gear37, and a second bearing38. The first input shaft31is substantially cylindrical, and a diameter of the first input shaft31is smaller than a diameter of the first robot arm10. The first input shaft31is coaxially received in the first robot arm10, and the first input shaft31rotates around the first axis A. An end311of the first input shaft31is substantially coplanar with an end11of the first robot arm10.

A shape of the first axle base33is substantially configured to be a shape of a cylinder cut along a line intersecting with an axis of the cylinder, and thus a longitudinal sectional view of the first axle base33is substantially triangular. The first axle base33includes a first opening end331, and a second opening end333opposite to the first opening end331. A diameter of the first opening end331is substantially equal to a diameter of the end11of the first robot arm10that is substantially coplanar with the first input shaft31. A diameter of the second opening end333is substantially greater than the diameter of the first opening end331. An axis of the second opening end333is defined as a second axis B. The second axis B is inclined relative to an axis of the first opening end331. The first opening end331is fastened to the end11of the first robot arm10, and thus the axis of the first opening end331overlaps with the first axis A. The first axis A is inclined relative to the second axis B.

A diameter of the first bevel gear35is substantially equal to a diameter of the first input shaft31. The first bevel gear35is mounted on the first opening end331of the first axle base33, and is fixed to the first input shaft31by fasteners, which enables the first input shaft31to rotate the first bevel gear35. The first bearing36is sleeved on a connecting portion of the first input shaft31and the first bevel gear35, to avoid a rotation of the first axle base33following a rotation of the first bevel gear35or a rotation of the first input shaft31.

The second bevel gear37is mounted on the second opening end333of the first axle base33, and is connected to the third robot arm50, thus the second bevel gear37rotates around the second axis B. An end of the second bevel gear37adjacent to the first bevel gear35meshes with the first bevel gear35, and thus the first bevel gear35rotates the second bevel gear37. The second bearing38is sleeved on the second bevel gear37, to avoid a rotation of the first axle base33following a rotation of the second bevel gear37.

The third robot arm50includes a second input shaft51, a second axle base52, a third bevel gear53, a third bearing54, a fourth bevel gear55, a fifth bevel gear56, a fourth bearing57, an output shaft58, and a fifth bearing59.

The second input shaft51is substantially cylindrical, and a diameter of the second input shaft51is substantially smaller than that of the first input shaft31. The second input shaft51is coaxially received in the first input shaft31, thus the second input shaft51rotates around the first axis A. An end511of the second input shaft51is substantially coplanar with the end311of the first input shaft31.

A shape of the second axle base52is substantially configured in a shape of a frustum cut along a line intersecting with an axis of the frustum. The second axle base52is located at a side of the second input shaft51adjacent to the second bevel gear37, and includes a third opening end521and a fourth opening end523opposite to the third opening end521. The third opening end521is substantially ring-like, and a diameter of the third opening end521is substantially smaller that that of the second opening end333of the first axle base33. The fourth opening end523is substantially a ring, and a diameter of the fourth opening end523is substantially smaller than that of the third opening end521. An axis of the third opening end521is inclined relative to an axis of the fourth opening end523. An inclined angle between the axis of the third opening end521and the axis of the fourth opening end523is substantially equal to an inclined angle between the axis of the first opening end331and the axis of the second opening end333. The third opening end521is located opposite to the second opening end333, and is fastened to the second bevel gear37. Thus, the axis of the third opening end521substantially overlaps the second axis B, and the axis of the fourth opening end523substantially overlaps the first axis A.

A diameter of the third bevel gear53is substantially equal to a diameter of the second input shaft51. The third bevel gear53is mounted in the first opening end331of the first axle base33, and is fastened to the second input shaft51, which enables the second input shaft53to rotate the third bevel gear53. The third bearing54is sleeved on a connecting portion of the third bevel gear53and the second input shaft51, thus the third bevel gear53and the first bevel gear35can rotate freely.

The fourth bevel gear55is coaxially received in the second bevel gear37, and an end of the fourth bevel gear55located adjacent to the third bevel gear53meshes with the third bevel gear53. The fifth bevel gear56is coaxially received in the third opening end521, and meshes with the fourth bevel gear55. The fourth bevel gear55rotates around the second axis B. The fifth bevel gear56rotates around the second axis B. The fourth bearing57is sleeved on a connecting portion of the fifth bevel gear56and the fourth bevel gear55, to avoid a rotation of the second axle base52and the second bevel gear37following a rotation of the fifth bevel gear56or a rotation of the fourth bevel gear55.

The output shaft58is substantially cylindrical, mounted in the fourth opening end523, and is fastened to the fifth bevel gear56, thus the fifth bevel gear56rotates the output shaft58around the second axis B. The fifth bearing59is mounted between the second axle base52and the output shaft58, to avoid a rotation of the second axle base52following a rotation of the output shaft58.

The flexible cable receiving tube70is substantially cylindrical, and is inserted into the third bevel gear53, the fourth bevel gear55, the fifth bevel gear56, and the output shaft58. An end of the flexible cable receiving tube70communicates with the second input shaft51, and the other end of the flexible cable receiving tube70is fixed on the output shaft58, to receive cables carrying electrical power or liquids. The flexible cable receiving tube70is positioned along the first axis A, and rotates around the first axis A.

In assembly, the third bevel gear53is fixed on the second input shaft51, and the third bearing54is sleeved on a connecting portion of the third bevel gear53and the second input shaft51. The first input shaft31is sleeved on the second input shaft51. The first bevel gear35is sleeved on the third bearing54, and is fixed to the first input shaft31. The first bearing36is sleeved on the first bevel gear35. The first robot arm10is sleeved on the first input shaft31. The first axle base33is sleeved on the first bearing36, and is fixed to the first opening end331. The fourth bevel gear55is mounted on the second opening end333, and meshes with the third bevel gear53. The fifth bevel gear56is mounted on the second opening end333, and meshes with the fourth bevel gear55. The output shaft58is fixed to the fifth bevel gear56. The fifth bearing59is sleeved on the output shaft58. The fourth bearing57is sleeved on a meshing portion of the fifth bevel gear56and the fourth bevel gear55. The second bevel gear37is sleeved on the fourth bearing57. The second axle base52is sleeved on the fifth bearing59, and the second bevel gear37is fixed to the third opening end521. The second bearing38is mounted between the second bevel gear37and the first axle base33. The flexible cable receiving tube70is inserted into the third bevel gear53, the fourth bevel gear55, the fifth bevel gear56, and the output shaft58, and is fixed to the output shaft58.

In use, cables carrying liquids, for example, are inserted into the flexible cable receiving tube70, and extend to the output shaft58. The first robot arm10rotates around the first axis A, and then drives the first axle base33to rotate around the first axis A. The first input shaft31rotates around the first axis A, and then the second axle base52rotates around the second axis B when driven by the first bevel gear35and the second bevel gear37. The second input shaft51rotates around the first axis A, and then the output shaft58rotates around the first axis A when driven by the third bevel gear53, the fourth bevel gear55, and the fifth bevel gear56, and thus rotates the flexible cable receiving tube70around the first axis A.

In an alternative embodiment, the first robot arm10, the first input shaft31, and the second input shaft51do not rotate along a same axis, and may rotate along different parallel axes. An axis of the first opening end331may be parallel to the first axis A. An axis of the second opening end333may be parallel to the second axis B.