Patent ID: 12226898

DESCRIPTION OF EXEMPLARY EMBODIMENTS

A driving mechanism and a robot according to the present disclosure are explained in detail below with reference to embodiments shown in the accompanying drawings.

For convenience of explanation, an X axis, a Y axis, and a Z axis, which are three axes orthogonal to one another, are shown in the figures. In the following explanation, the upper side of the figures, that is, an arrow side of the Z axis is represented as the upper side of the vertical direction and the lower side of the figures, that is, the opposite side of the arrow of the Z axis is represented as the lower side in the vertical direction. “Parallel” in this specification has a meaning including, other than parallelism, a state slightly deviating from the parallelism, that is, has a meaning including a state regarded as the same as the parallelism based on the common general knowledge. Similarly, “orthogonal” in this specification has a meaning including, other than orthogonality, a state slightly deviating from the orthogonality, that is, has a meaning including a state regarded the same as the orthogonality based on the common general knowledge.

First Embodiment

FIG.1is a side view showing an overall configuration of a robot according to a first embodiment. FIG.2is a plan view showing an internal structure of a second arm included in the robot shown inFIG.1.FIG.3is a sectional view showing a driving mechanism included in the second arm shown inFIG.2.

A robot100shown inFIG.1is a SCARA robot and is used in work such as holding, conveyance, assembly, and inspection of a workpiece such as an electronic component. However, a use of the robot100is not particularly limited.

The robot100includes a base110fixed to a floor surface and an arm120coupled to the base110. The arm120includes a first arm130, the proximal end portion of which is coupled to the base110, the first arm130turning around a first turning axis J1, which extends along the vertical direction, with respect to the base110, and a second arm140, the proximal end portion of which is coupled to the distal end portion of the first arm130, the second arm140turning around a second turning axis J2, which extends along the vertical direction, with respect to the first arm130. The first turning axis J1and the second turning axis J2are parallel.

A work head150is provided at the distal end portion of the second arm140. The work head150includes a spline nut151and a ball screw nut152coaxially disposed at the distal end portion of the second arm140and a spline shaft153inserted through the spline nut151and the ball screw nut152. The spline shaft153is capable of rotating around a third turning axis J3, which is the center axis of the second arm140and extends along the vertical direction, with respect to the second arm140and is capable of rising and falling along the third turning axis J3. The third turning axis J3is parallel to the first turning axis J1and the second turning axis J2.

However, the work head150is not particularly limited. For example, the work head150may have a configuration in which two shafts are provided and one shaft rotates around the third turning axis J3and the other shaft rises and falls in an axial direction parallel to the third turning axis J3.

An end effector160is attached to the lower end portion of the spline shaft153. As the end effector160, an end effector detachably attachable and suitable for target work is selected as appropriate. Examples of the end effector160include a hand that holds a workpiece by clamping or attracting the work and a work tool that performs predetermined machining on the workpiece.

The robot100includes a joint actuator171that couples the base110and the first arm130and turns the first arm130around the first turning axis J1with respect to the base110and a joint actuator172that couples the first arm130and the second arm140and turns the second arm140around the second turning axis J2with respect to the first arm130. The robot100includes a driving mechanism181that rotates the spline nut151and rotates the spline shaft153around the third turning axis J3and a driving mechanism182that rotates the ball screw nut152and lifts and lowers the spline shaft153in a direction along the third turning axis J3.

The robot100includes a robot control device190that is disposed in the base110and controls driving of the joint actuators171and172and the driving mechanisms181and182based on a command from a not-shown host computer. The robot control device190can cause the robot100to perform desired work by controlling the joint actuators171and172and the driving mechanisms181and182independently from one another. The robot control device190is configured from, for example, a computer and includes a processor that processes information, a memory communicably coupled to the processor, and an external interface. Various programs executable by the processor are stored in the memory. The processor can read and execute the various programs and the like stored in the memory.

The overall configuration of the robot100is briefly explained above. Subsequently, the driving mechanism181that rotates the spline nut151and rotates the spline shaft153around the third turning axis J3is explained in detail with reference toFIGS.2and3.

As shown inFIGS.2and3, the driving mechanism181includes a motor2functioning as a driving source. The motor2is fixed to a housing141of the second arm140. An output shaft21of the motor2rotates around a first axis JJ1extending along the vertical direction. The motor2is an AC servomotor. However, the motor2is not particularly limited. For example, a DC servomotor or a stepping motor may be used as the motor2.

The driving mechanism181includes a first pulley31, which is disposed in the output shaft21of the motor2and rotates around the first axis JJ1integrally with the output shaft21. The lower end of the output shaft21is a free end. The first pulley31can be detached from the lower end side. In this embodiment, the first pulley31is directly disposed in the output shaft21. However, not only this, but, for example, a mechanism such as a power transmission mechanism or a speed reducer including a gear may be interposed between the output shaft21and the first pulley31.

The driving mechanism181includes a second pulley32that is disposed to be separated from the first pulley31and rotates around a second axis JJ2parallel to the first axis JJ1. The second pulley32is disposed on the distal end side of the second arm140with respect to the first pulley and located between the spline shaft153and the first pulley31. The second pulley32is disposed side by side with the first pulley31in a direction along an X-Y plane. However, the disposition of the second pulley32is not particularly limited.

The driving mechanism181includes a first belt41that is laid around the first pulley31and the second pulley32and couples the first pulley31and the second pulley32. Therefore, when the first pulley31rotates, the rotation is transmitted to the second pulley32via the first belt41. The second pulley32rotates following the first pulley31. The outer diameter of the second pulley32is larger than the outer diameter of the first pulley31. Therefore, a first speed reducer51that reduces the rotation speed of the output shaft21of the motor2is configured by the first pulley31, the first belt41, and the second pulley32.

The driving mechanism181includes a third pulley33that is disposed side by side with the second pulley32in a direction along the second axis JJ2and rotates around the second axis JJ2. The third pulley33rotates integrally with the second pulley32. The outer diameter of the third pulley33is smaller than the outer diameter of the second pulley32.

The driving mechanism181includes a fourth pulley34that is disposed to be separated from the third pulley33and rotates around a third axis JJ3parallel to the first and second axes JJ1and JJ2. The fourth pulley34is disposed on the distal end side of the second arm140with respect to the third pulley33and disposed coaxially with the spline shaft153. That is, the third axis JJ3coincides with the third turning axis J3. The spline nut151is inserted through and fixed to the fourth pulley34. The fourth pulley34and the spline nut151integrally rotate. The fourth pulley34is disposed side by side with the third pulley33in the direction along the X-Y plane. However, the disposition of the fourth pulley34is not particularly limited.

The driving mechanism181includes a second belt42that is laid around the third pulley33and the fourth pulley34and couples the third pulley33and the fourth pulley34. Therefore, when the third pulley33rotates, the rotation is transmitted to the fourth pulley34via the second belt42. The fourth pulley34rotates following the third pulley33. The outer diameter of the fourth pulley34is larger than the outer diameter of the third pulley33. Therefore, a second speed reducer52that reduces the rotation speed of the output shaft21of the motor2is configured by the third pulley33, the second belt42, and the fourth pulley34.

The configuration of the driving mechanism181is not limited to this. For example, the driving mechanism181may include an idler that applies tension to the second belt42.

In such a driving mechanism181, a driving force of the motor2is transmitted to the spline nut151via the first speed reducer51and the second speed reducer52. By interposing the first and second speed reducers51and52between the motor2and the spline nut151in this way, it is possible to rotate the spline nut151at desired rotation speed. Flexibility of disposition of the motor2increases. The second arm140is easily designed.

In particular, by disposing the two speed reducers between the motor2and the spline nut151, the outer diameter of the fourth pulley34can be set smaller than when one speed reducer is disposed. Therefore, it is possible to suppress an increase in the size and an increase in the weight of the distal end portion of the second arm140. It is possible to realize the robot100having an excellent driving characteristic. For example, when it is desired to reduce the rotation speed of the fourth pulley34to 1/9 of the rotation speed of the output shaft21, in the configuration in this embodiment, a pulley ratio of the first speed reducer51only has to be set to 3 and a pulley ratio of the second speed reducer52only has to be set to 3. Therefore, it is possible to suppress an excessive increase in the diameter of the fourth pulley34. In contrast, in the case of only the second speed reducer52, that is, when the first speed reducer51is omitted and the third pulley33is disposed in the output shaft21, the pulley ratio of the second speed reducer52has to be set to9. This causes an excessive increase in the diameter of the fourth pulley34.

The driving mechanism181includes a first bearing61disposed between the second pulley32and the third pulley33. The driving mechanism181includes a second bearing62located on the lower side of the third pulley33and disposed to sandwich the third pulley33between the second bearing62and the first bearing61. That is, on the second axis JJ2, the second bearing62, the third pulley33, the first bearing61, and the second pulley32are disposed side by side from the lower side. The first bearing61and the second bearing62respectively support the second pulley32and the third pulley33rotatably around the second axis JJ2. The second pulley32is supported at one end from the lower side by the first bearing61. The third pulley33is supported at both ends from above and below by the first bearing61and the second bearing62.

Since the rotation speed of the output shaft21is reduced by the first speed reducer51, torque larger than torque applied to the first belt41is applied to the second belt42. Therefore, in order to maintain durability, the rigidity of the second belt42needs to be set larger compared with the first belt41. Accordingly, the tension of the second belt42also increases. As a result, a radial load larger than a radial load applied to the second pulley32is applied to the third pulley33. Therefore, by supporting the third pulley33at both ends with the first bearing61and the second bearing62as in this embodiment, it is possible to more effectively suppress displacement of the third pulley33caused by the radial load. Therefore, the rotation of the third pulley33is stabilized. Compared with when the third pulley33is supported at one end by one bearing, the first bearing61and the second bearing62can be reduced in size. However, not only this, but the second bearing62may be omitted.

The first bearing61and the second bearing62are respectively not particularly limited. In this embodiment, a deep groove ball bearing is used as the first bearing61and the second bearing62. The deep groove ball bearing can receive a radial load, an axial load in both directions, or a combined load obtained by combining the radial load and the axial load. The deep groove ball bearing can cope with high-speed rotation. Since the deep groove ball bearing is widely used, it is possible to realize a reduction in cost.

The first bearing61includes an inner ring611and an outer ring612disposed concentrically with each other and a plurality of balls613disposed between the inner ring611and the outer ring612. Similarly, the second bearing62includes an inner ring621and an outer ring622disposed concentrically with each other and a plurality of balls623disposed between the inner ring621and the outer ring622. The outer rings612and622of the first and second bearings61and62are fixed to the housing141of the second arm140. A shaft section7extending along the second axis JJ2is inserted into and fixed to the inner rings611and621. The second pulley32and the third pulley33are fixed to the shaft section7. With such a configuration, the second pulley32and the third pulley33can integrally rotates around the second axis JJ2.

The upper end of the shaft section7is a free end. Therefore, as explained below, it is possible to detach the first belt41from the second pulley32without being hindered by the shaft section7.

Fixing of the first and second bearings61and62to the second arm140is explained. The driving mechanism181includes a coupling section8that couples the outer rings612and622of the first and second bearings61and62to each other. The coupling section8is fixed to the housing141of the second arm140. Consequently, the first and second bearings61and62are collectively fixed to the housing141of the second arm140. With such a configuration, it is easy to fix the first and second bearings61and62to the second arm140. However, a method of fixing the first and second bearings61and62to the second arm140is not particularly limited.

The coupling section8includes a first bearing supporting section81that supports the outer ring612of the first bearing61, a second bearing supporting section82that supports the outer ring622of the second bearing62and is fixed to the housing141of the second arm140, and a coupling section83that couples the first bearing supporting section81and the second bearing supporting section82. The second bearing supporting section82and the coupling section83are integrally formed. The coupling section83and the first bearing supporting section81are screwed. However, the configuration of the coupling section8is not limited to this. For example, the first bearing supporting section81, the second bearing supporting section82, and the coupling section83may be respectively configured by different members.

The coupling section83passes the inner side of the second belt42laid around the third pulley33and the fourth pulley34in a ring shape and couples the first bearing supporting section81and the second bearing supporting section82. That is, the coupling section8passes the inner side of the second belt42and couples the first bearing61and the second bearing62.

The configuration of the driving mechanism181is explained above. With the driving mechanism181, it is possible to easily detach and attach the first belt41at the time of work such as repair, maintenance, and inspection. Specifically, the first belt41is loosened by detaching the first pulley31from the output shaft21. The first belt41can be detached from the first pulley31and the second pulley32. When the first belt41is attached, the opposite procedure only has to be performed. After the first belt41is laid around the first pulley31and the second pulley32, the first pulley31only has to be fixed to the output shaft21. In this way, with the driving mechanism181, it is possible detach and attach the first belt41only by detaching and attaching the first pulley31. Therefore, it is easy to detach and attach the first belt41.

The second belt42is loosened by detaching the work head150from the second arm140and setting the fourth pulley34free. The second belt42can be detached from the third pule33and the fourth pulley34. When the second belt42is attached, the opposite procedure only has to be performed. After the second belt42is laid around the third and fourth pulleys33and34, the work head150only has to be inserted into and fixed to the housing141of the second arm140. In this way, with the driving mechanism181, it is possible to detach and attach the second belt42only by detaching and attaching the work head150. Therefore, it is easy to detach and attach the second belt42. In particular, in this embodiment, the coupling section8passes the inner side of the second belt42and couples the first bearing61and the second bearing62. Therefore, it is possible to smoothly detach the second belt42without being hindered by the coupling section8.

For example, when the driving mechanism181includes an idler that applies tension to the second belt42, by loosening the idler, it is possible to detach the second belt42from the third pulley33and the fourth pulley34without detaching the work head150.

If a belt is once loosened, tension needs to be applied to the belt when the belt is attached again. Work for applying the tension requires labor. Therefore, if the second belt42needs to be detached in order to detach the first belt41, work for applying tension to each of the first and second belts41and42again is necessary. Therefore, considerable labor is required. The same occurs when the first belt41needs to be detached in order to detach the second belt42. In contrast, with the driving mechanism181, it is unnecessary to detach the second belt42in order to detach the first belt41and it is unnecessary to detach the first belt41in order to detach the second belt42. Therefore, the labor of the work for applying tension again at the time when the belt is attached again is reduced.

The robot100is explained above. The driving mechanism181included in such a robot100includes, as explained above, the first pulley31that rotates around the first axis JJ1, the motor2that rotates the first pulley31around the first axis JJ1, the second pulley32that is disposed to be separated from the first pulley31and rotates around the second axis JJ2parallel to the first axis JJ1, the first belt41that is laid around the first pulley31and the second pulley32and transmits power of the motor2from the first pulley31to the second pulley32, the third pulley33that is disposed side by side with the second pulley32in the direction along the second axis JJ2and rotates around the second axis JJ2integrally with the second pulley32, the fourth pulley34that is disposed to be separated from the third pulley33and rotates around the third axis JJ3parallel to the second axis JJ2, the second belt42that is laid around the third pulley33and the fourth pulley34and transmits the power of the motor2from the third pulley33to the fourth pulley34, and the first bearing61that is located between the second pulley32and the third pulley33and supports the second pulley32and the third pulley33. With such a configuration, even when it is desired to obtain a large reduction ratio, it is possible to reduce the outer diameter of the fourth pulley34. Therefore, it is possible to suppress an increase in the size and an increase in the weight of the distal end portion of the second arm140. It is possible to realize the robot100having an excellent driving characteristic. It is unnecessary to detach the second belt42in order to detach the first belt41. It is unnecessary to detach the first belt41in order to detach the second belt42. Therefore, it is easy to detach and attach the first belt41. The labor of the work for applying tension again when the belt is attached again is reduced.

As explained above, the driving mechanism181includes the second bearing62that is disposed to sandwich the third pulley33between the second bearing62and the first bearing61and supports the third pulley33. Consequently, the third pulley33is supported at both ends by the first bearing61and the second bearing62. Therefore, it is possible to more effectively suppress displacement of the third pulley33caused by the tension of the second belt42. The rotation of the third pulley33is stabilized. Compared with when the third pulley33is supported at one end only by the first bearing61, the first bearing61and the second bearing62can be reduced in size.

As explained above, the driving mechanism181includes the coupling section8that passes the inner side of the second belt42and couples the first bearing61and the second bearing62. Consequently, it is possible to detach and attach the second belt42without being hindered by the coupling section8.

As explained above, the robot100includes the driving mechanism181. Therefore, the robot100can enjoy the effect of the driving mechanism181and exert high maintainability.

Second Embodiment

FIG.4is a sectional view showing a driving mechanism included in a robot according to a second embodiment.

The robot100in this embodiment is the same as the robot100in the first embodiment except that the disposition of the second bearing62and the configuration of the coupling section8are different. In the following explanation, concerning this embodiment, differences from the first embodiment are mainly explained. Explanation about similarities to the first embodiment is omitted. InFIG.4, the same components as the components in the first embodiment are denoted by the same reference numerals and signs.

As shown inFIG.4, in the driving mechanism181in this embodiment, the second bearing62is located on the upper side of the second pulley32and is disposed to sandwich the second pulley32between the second bearing62and the first bearing61. Therefore, the second pulley32is supported at both ends from above and below by the first bearing61and the second bearing62. The third pulley33is supported at one end from the upper side by the first bearing61. With such a configuration, the second pulley32can be supported in a more stable posture. The rotation of the second pulley32is stabilized. Compared with when the second pulley32is supported at one end only by the first bearing61, the first bearing61and the second bearing62can be reduced in size.

The coupling section8includes the first bearing supporting section81that supports the outer ring612of the first bearing61and is fixed to the housing141of the second arm140, the second bearing supporting section82that supports the outer ring622of the second bearing62, and the coupling section83that couples the first bearing supporting section81and the second bearing supporting section82. The first bearing supporting section81and the coupling section83are integrally formed. The coupling section83and the second bearing supporting section82are screwed. However, the configuration of the coupling section8is not limited to this.

The coupling section83passes the inner side of the first belt41laid around the first pulley31and the second pulley32in a ring shape and couples the first bearing supporting section81and the second bearing supporting section82. That is, the coupling section8passes the inner side of the first belt41and couples the first bearing61and the second bearing62. Consequently, work for detaching the first pulley31from the output shaft21and detaching the first belt41from the first pulley31and the second pulley32is not hindered by the coupling section8. The work can be smoothly performed.

As explained above, the driving mechanism181in this embodiment includes the second bearing62that is disposed to sandwich the second pulley32between the second bearing62and the first bearing61and supports the second pulley32. Consequently, the second pulley32is supported at both ends by the first bearing61and the second bearing62. Therefore, the rotation of the second pulley32is further stabilized. Compared with when the second pulley32is supported at one end by only the first bearing61, the first bearing61and the second bearing62can be reduced in size.

As explained above, the driving mechanism181includes the coupling section8that passes the inner side of the first belt41and couples the first bearing61and the second bearing62. Consequently, it is possible to detach and attach the first belt41without being hindered by the coupling section8.

According to the second embodiment explained above, the same effects as the effects of the first embodiment can be exerted.

Third Embodiment

FIG.5is a sectional view showing a driving mechanism included in a robot according to a third embodiment.

The robot100in this embodiment is the same as the robot100in the first embodiment except that the driving mechanism181further includes a brake9. In the following explanation, concerning this embodiment, differences from the embodiments explained above are mainly explained. Explanation about similarities to the embodiments explained above is omitted. InFIG.5, the same components as the components in the embodiments explained above are denoted by the same reference numerals and signs.

As shown inFIG.5, the driving mechanism181in this embodiment includes the brake9that restricts the rotation of the pulleys31,32,33, and34. The brake9is provided in the shaft section7and restricts the rotation of the shaft section7to thereby restrict the rotation of the pulleys31,32,33, and34. The brake9is not particularly limited if the brake9can switch a state in which the rotation of the shaft section7is restricted and a state in which the rotation of the shaft section7is allowed.

In particular, the brake9is disposed on the lower side of the second bearing62. Consequently, for example, compared with when the brake9is disposed on the upper side of the second pulley32, since a member is not interposed between the brake9and the second bearing62, the brake9can be disposed near the second bearing62. Therefore, the rotation of the shaft section7can be stably restricted by the brake9. Since the brake9is disposed on the lower side of the second bearing62, the brake9less easily affects detachment and attachment of the first belt41.

According to the third embodiment explained above, the same effects as the effects of the first embodiment can be exerted.

Fourth Embodiment

FIG.6is a sectional view showing a driving mechanism included in a robot according to a fourth embodiment.

The robot100in this embodiment is the same as the robot100in the second embodiment except that the driving mechanism181further includes the brake9. In the following explanation, concerning this embodiment, differences from the embodiments explained above are mainly explained. Explanation about similarities to the embodiments explained above is omitted. InFIG.6, the same components as the components in the embodiments explained above are denoted by the same reference numerals and signs.

As shown inFIG.6, the driving mechanism181in this embodiment includes the brake9that restricts the rotation of the pulleys31,32,33, and34. The brake9is provided in the shaft section7and restricts the rotation of the shaft section7to thereby restrict the rotation of the pulleys31,32,33, and34. The brake9is not particularly limited if the brake9can switch a state in which the rotation of the shaft section7is restricted and a state in which the rotation of the shaft section7is allowed.

In particular, the brake9is disposed on the upper side of the second bearing62. Consequently, for example, compared with when the brake9is disposed on the lower side of the third pulley33, since a member is not interposed between the brake9and the second bearing62, the brake9can be disposed near the second bearing62. Therefore, the rotation of the shaft section7can be stably restricted by the brake9. In a plan view along the Z axis, the brake9is fixed to the housing141of the second arm140via the coupling section8on the inner side of the first belt41. Consequently, the brake9less easily affects detachment and attachment of the first belt41.

According to the fourth embodiment explained above, the same effects as the effects of the first embodiment can be exerted.

The driving mechanism and the robot according to the present disclosure are explained above with reference to the embodiments shown in the figures. However, the present disclosure is not limited to this. The components of the sections can be replaced with any components having the same functions. Any other components may be added to the present disclosure. The driving mechanism may be applied to any equipment other than the robot.