JP3801059B2 - Robot joint structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
According to the present invention, the second arm frame is rotatably connected to the first arm frame via the shaft portion, and the cable passage is located on the outer peripheral side of the shaft portion to the second arm frame. The present invention relates to a joint structure of a robot in which a wiring insertion hole is provided.
[0002]
[Problems to be solved by the invention]
For example, in an articulated robot in which a plurality of arms are rotatably connected in sequence, wiring (cable) is passed through the arm. For example, in a small horizontal articulated robot, in the joint portion of the first arm and the second arm, the frame of the second arm is rotatably connected to the frame of the first arm. A cable (wiring) is passed through an insertion hole formed in the frame of the arm.
[0003]
In this case, the insertion hole extends in an arc shape in the circumferential direction in order to prevent the cable from being sandwiched between the frames of the first arm and eventually disconnected as the second arm rotates relative to the first arm. As a long hole shape, it is considered that the cable can move relatively in the insertion hole. In this case, the rotation range of the second arm with respect to the first arm is restricted in terms of software and hardware, but the cable passes through the insertion hole as a long hole. By being able to move, a relatively wide rotation range can be secured.
[0004]
However, even if the insertion hole is a long hole as described above, the cable is not caught, but when the second arm rotates to the position where the insertion hole wraps around the frame of the first arm when viewed in the axial direction, the cable May directly contact the frame of the first arm made of metal (casting), so that there is still a possibility that the cable may be rubbed to damage the coating or to be broken if it gets worse.
[0005]
The present invention has been made in view of the above circumstances, and an object thereof is to provide a wiring insertion hole that is located on the outer peripheral side of the shaft portion and serves as a cable passage, and the cable is provided in the frame of the arm. It is an object of the present invention to provide a joint structure of a robot that can prevent direct contact and protect a cable.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the joint structure of the robot according to the present invention has a wiring insertion hole provided in the frame of the second arm formed in a long hole shape extending in the circumferential direction, and the cable is inserted into the wiring. The inside of the hole is provided in a state of being held by an inner cable holder that is slidably movable in the circumferential direction, and the inner cable holder is moved to the first arm according to relative rotation of the second arm with respect to the first arm. It is comprised so that it may contact | abut to this flame | frame (invention of Claim 1).
[0007]
According to this, when the cable is passed through the wiring insertion hole while being held by the inner cable holder, the second arm rotates to a position where the wiring insertion hole wraps on the frame of the first arm. Even so, the cable can be prevented from coming into direct contact with the frame of the first arm only by the inner cable holder abutting against the frame of the first arm. Further, even when the inner cable holder abuts against the frame of the first arm, the second inner cable holder relatively slides in the elongated hole insertion hole while holding the cable. The required rotation range of the first arm relative to the first arm can be ensured.
[0008]
Therefore, according to the joint structure of the robot of the first aspect, the cable is prevented from coming into direct contact with the frame of the first arm while ensuring the function required for the wiring insertion hole, thereby protecting the cable. In addition, a simple configuration in which only an inner cable holder is provided can be achieved. The first arm referred to in the present invention means one arm, the second arm means another arm that is rotationally connected to the arm, and a specific position in the entire robot arm. Of course, it does not indicate the arm of the order.
[0009]
In this case, the wiring insertion hole is provided with an outer cable guide formed in a cylindrical shape that is curved in an arc shape from the plastic in the extending direction of the wiring insertion hole, and the plastic inner cable holder is provided in the outer cable guide. Can be slidably supported (invention of claim 2). According to this, since the sliding movement is performed by sliding between the plastic members, the sliding movement of the inner cable holder is smoothly performed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a small horizontal articulated (four-axis) robot will be described with reference to the drawings. FIG. 4 shows the external configuration of the main body 1 of the horizontal articulated robot in the present embodiment in a state where it is at the origin position. First, the entire configuration of the robot main body 1 will be briefly described.
[0011]
That is, on the base 2 fixedly installed on the installation surface of the equipment, the base end portion (the right end portion in the drawing) of the first arm 3 extending leftward in the drawing rotates (turns around the vertical axis J1). ) Connected possible. A base end portion (right end portion in the figure) of the second arm 4 extending leftward in the drawing is connected to the top surface of the distal end of the first arm 3 so as to be rotatable (turnable) about the vertical axis J2. . At the tip of the second arm 4, a vertical arm 5 having a shaft shape extending vertically is provided so as to be vertically movable and coaxially rotatable. A tool such as a hand (not shown) is detachably attached to the tip (lower end) of the upper and lower arms 5.
[0012]
Although not shown in detail, a single-axis servomotor for rotating the first arm 3 with respect to the base 2 is disposed in the base 2. At the same time, in the second arm 4, a two-axis servomotor 6 (see FIG. 1) for rotating the second arm 4 with respect to the first arm 3, and the vertical arm 5 for moving up and down. A Z-axis servo motor, a T-axis servo motor for coaxially driving the upper and lower arms 5 and the like are provided.
[0013]
Further, a robot controller (not shown) is connected to the robot body 1 (base 2), and the motors are controlled by the robot controller. Accordingly, in the robot body 1, as shown only in part in FIG. 1, a cable (wiring) 7 is passed from the base 2 through the first arm 3 to the second arm 4. .
[0014]
Next, FIG. 1 and FIG. 2 show the configuration of the joint portion that connects the first arm 3 and the second arm 4, particularly the second arm 4 portion, at the origin position of the robot body 1. The section includes the joint structure according to the present embodiment. In this case, the first arm 3 functions as the first arm according to the present invention, and the second arm 4 functions as the second arm according to the present invention. Hereinafter, this joint structure will be described in detail.
[0015]
First, as shown in FIG. 1, the first arm 3 has an outer shell made of a metal (cast) frame 8 having a generally thin box shape (hollow shape) as a whole. As shown in FIGS. 2 and 3, a substantially circular connecting portion 8 a for connecting the second arm 4 is provided on the left end side of the upper wall portion. The left and front and rear portions of the periphery of the connecting portion 8a are open, and a constricted portion 8b that is constricted in the front and rear is formed on the right side of the connecting portion 8a. The bottom wall portion at the left end of the frame 8 is open, and the opening is closed by a removable lower cover 9.
[0016]
On the other hand, the outer arm of the second arm 4 is composed of a box-shaped metal (cast) frame 10 and its upper surface is covered with a removable upper cover 11. The two-axis servomotor 6 and the speed reducer unit 12 are incorporated in the right part of the figure in the frame 10. At this time, a cylindrical mounting tube portion 10a is integrally formed on the lower surface side of the right end portion in the drawing of the frame 10 so as to correspond to the connecting portion 8a, and the speed reducer is provided inside the mounting tube portion 10a. The unit 12 is incorporated, and the two-axis servomotor 6 is fixed downward by bolting to the upper end portion of the mounting cylinder portion 10a.
[0017]
The speed reducer unit 12 is formed by integrating a bearing (cross roller bearing) 13 and a speed reducer, for example, a known harmonic drive, and is disposed on the outer periphery of a wave generator 14 having a ball bearing on the outer periphery of an elliptical cam. The cup-shaped flexspline (elastic gear) 15 and the circular spline (internal gear) 16 meshing with the outer periphery of the cup-shaped flexspline (elastic gear) 15 are provided.
[0018]
At this time, the rotary shaft 6a of the two-axis servomotor 6 is connected to the wave generator 14, and the circular spline 16 is fixed to the mounting cylinder portion 10a of the frame 10 by bolting. Further, a ring-shaped output shaft 18 as a shaft portion is connected to the tip (lower end) of the flex spline 15 via an attachment member 17. In this case, the output shaft 18 also serves as an inner ring of the bearing 13, and the two outer rings of the bearing 13 are fixed to the mounting cylinder 10a by bolting. An oil seal 19 is provided between the inner and outer rings at the tip (lower end) of the bearing 13.
[0019]
The output shaft 18 is fixed to the connecting portion 8a of the frame 8 of the first arm 3 by bolting. Thus, when the two-axis servomotor 6 is driven to rotate, the rotation is decelerated by the reduction gear unit 12 and transmitted to the output shaft 18. At this time, the output shaft 18 first arm 3 is driven. The second arm 4 (frame 10) is fixed to the first arm 3 in the directions of arrows A and B with respect to the vertical axis J2 (see FIGS. 2 and 3). It will be rotated.
[0020]
The robot controller is provided with a so-called soft limit that restricts the rotation range of the second arm 4 with respect to the first arm 3 in terms of software. Is provided with a mechanical stopper mechanism for mechanically restricting the rotation range of the second arm 4 relative to the first arm 3. In this case, the rotation range restricted by the mechanical stopper mechanism (for example, 147.8 ° on both sides from the origin position shown in FIG. 2 etc.) is more than the rotation range restricted by the soft limit (145 ° on both sides from the origin position). It is somewhat larger.
[0021]
As shown in FIGS. 1 to 3, the frame 10 of the second arm 4 is positioned on the left side of the outer peripheral side of the mounting tube portion 10 a (the connecting portion 8 a), and the cable 7. A wiring insertion hole 10b serving as a passage is formed. In this case, the wiring insertion hole 10b has a certain depth (height) and is formed in a long hole shape (arc shape around the rotation axis of the second arm 4) that is elongated along the circumferential direction. ing. Further, as shown in FIG. 3B, the wiring insertion hole 10b is located at a position (axial direction) corresponding to the constricted portion 8b of the frame 8 when the second arm 4 rotates with respect to the first arm 3. (Position to wrap as seen in FIG. 2).
[0022]
In this embodiment, an outer cable guide 20 is provided in the wiring insertion hole 10b, and the inner cable holder 21 is supported by the outer cable guide 20 so as to be slidable. FIG. 5 shows the configuration of the outer cable guide 20 and the inner cable holder 21, and the outer cable guide 20 is made of a plastic material (for example, polyacetal resin) and is a circle corresponding to the inner peripheral surface of the wiring insertion hole 10 b. It is formed in a cylindrical shape curved in an arc shape. Further, as shown in FIG. 5 (b), the outer cable guide 20 is formed with a slide groove 20a extending in the lateral direction (circumferential direction) near the lower portion of the inner wall surface on the front and rear sides (inner and outer peripheral sides). Further, screwing portions 20b are integrally provided on both end sides of the upper end portion.
[0023]
On the other hand, the inner cable holder 21 is formed from a similar plastic material (polyacetal resin) in a circular arc shape along the inner peripheral surface of the outer cable guide 20, and is formed in a cylindrical shape having a short dimension in the circumferential direction. ing. The inner cable holder 21 is large enough to allow the cable 7 to pass therethrough. Further, as shown in FIG. 5 (b), slide protrusions 21a that engage with the slide groove portions 20a are arranged in the lateral direction (in the vicinity of the upper end of the outer wall surface on the front and rear sides (inner and outer peripheral sides) of the inner cable holder 21 ( (Circumferential direction).
[0024]
As shown in FIG. 1 and the like, the outer cable guide 20 is attached to the frame 10 by screwing so as to be closely fitted in the wiring insertion hole 10b. The inner cable holder 21 is slidable in the outer cable guide 20 in the circumferential direction by engaging the slide protrusion 21a with the slide groove 20a in a state where the cable 7 is passed and held therein. Has come to be supported. At this time, as shown in FIG. 1 and FIG. 5B, a part of the inner cable holder 21 protrudes downward from the outer cable guide 20 (wiring insertion hole 10 b), and the protruding part is the frame 8. It is arranged at a height position corresponding to the connecting portion 8a.
[0025]
Thus, as will be described in the following description of the operation, the inner cable holder 21 holding the cable 7 is attached to the first arm 3 in response to the second arm 4 rotating relative to the first arm 3. The frame 8 (constriction 8b) is brought into contact with the outer cable guide 20 and is relatively slid. In this case, the outer cable guide 20 (wiring insertion hole 10b) and the inner cable holder 21 are formed in a size (position) corresponding to the rotation range of the second arm 4 with respect to the first arm 3. Of course. Further, this rotation range is ensured greatly by forming the constricted portion 8b in the frame 8 of the first arm 3.
[0026]
Next, the operation of the above configuration will be described. In the joint structure that connects the first arm 3 and the second arm 4 described above, the cable 7 is connected to the outside of the connecting portion 8 a of the frame 8 of the first arm 3 and the bearing 13 of the frame 10 of the second arm 4. The outer portion is passed between the arms 3 and 4 at the outer portion. At this time, the outer cable guide 20 is provided in the wiring insertion hole 10 b formed in the frame 10, and the cable 7 is connected to the inner cable holder 21. The outer cable guide 20 is passed through while being held.
[0027]
Now, for example, when the second arm 4 is at the origin position, as shown in FIGS. 2 and 3A, the inner cable holder 21 and the cable 7 are substantially at the center of the outer cable guide 20 (wiring insertion hole 10b). Is located. From this state, when the second arm 4 is rotated with respect to the first arm 3, for example, in the direction of arrow B (counterclockwise as viewed from above), the frame of the first arm 3 is viewed in the axial direction. 8 (constriction 8b) reaches the position where the wiring insertion hole 10b (outer cable guide 20) wraps, and finally the inner cable holder 21 is placed on the side of the constriction 8b of the frame 8 as shown in FIG. Come into contact.
[0028]
When the second arm 4 further rotates, the inner cable holder 21 slides relatively in the direction of arrow A in the outer cable guide 20 while holding the cable 7. Thereby, it is possible to prevent the cable 7 from being sandwiched between the frames 8 of the first arm 3 and eventually being disconnected. At this time, since the inner cable holder 21 and the outer cable guide 20 are both made of plastic, the inner cable holder 21 can be smoothly slid.
[0029]
Therefore, if the cable 7 may come into direct contact with the frame 8 of the first arm 3 made of metal (casting) during the operation of the second arm 4 described above, the cable 7 may be rubbed to damage or worsen the coating. There is a risk of disconnection. However, in the present embodiment, since the cable 7 is held by the inner cable holder 21, it does not come into direct contact with the frame 8, and is prevented from being damaged. The cable 7 does not directly contact the edge of the wiring insertion hole 10 b of the frame 10 of the second arm 4.
[0030]
Although illustration and description are omitted, the same effect can be obtained when the second arm 4 rotates in the opposite direction (arrow A direction). Further, in the above configuration, the wiring insertion hole 10b (outer cable guide 20) has a long hole shape extending in the circumferential direction, and the constricted portion 8b is provided in the frame 8 of the first arm 3, so that the second arm 4 A required rotation range for the first arm 3 can be ensured. Since the wiring insertion hole 10b is an elongated hole having a narrow width in the radial direction, the joint portion can be prevented from being enlarged in the radial direction, and the strength of the frame 10 can be secured.
[0031]
As described above, according to the joint structure of the robot of this embodiment, the cable 7 is prevented from coming into direct contact with the frame 8 of the first arm 3 while ensuring the function required for the wiring insertion hole 10b. The cable 7 can be protected, and a simple configuration in which the inner cable holder 21 is added can be achieved. In particular, in this embodiment, since the inner cable holder 21 is configured to slide on the inner surface of the same plastic outer cable guide 20, it is possible to obtain an advantage that the inner cable holder 21 slides smoothly. Can do.
[0032]
In the above embodiment, the present invention is applied to a horizontal articulated robot, but the present invention can be applied not only to a vertical articulated robot but also to robots of various structures. In this case, the first arm and the second arm referred to in the present invention mean one arm and another arm that is rotationally connected to the arm, such as a specific position in the entire robot arm, Of course, it does not indicate an arm of order. In addition, the present invention is within the scope not departing from the gist of the invention, such as the shape of the robot arm (frame), the arrangement of the servo motor, and the detailed configuration such as the configuration of the bearing and the speed reducer. It can be implemented with appropriate changes.
[Brief description of the drawings]
FIG. 1 shows an embodiment of the present invention, and is a longitudinal front view showing the structure of a joint portion of a connecting portion between a first arm and a second arm. FIG. 2 is a partially cutaway view of an upper cover. FIG. 3 is a bottom view showing a state in which the second arm is at the origin position (a) and a state in which the second arm is rotated with respect to the first arm (b) with the lower cover removed. FIG. 5 is a perspective view (a) and a longitudinal cross-sectional view (b) of the state where the inner cable holder is held by the outer cable guide.
[Explanation of symbols]
In the drawings, 1 is a robot body, 3 is a first arm (first arm), 4 is a second arm (second arm), 7 is a cable, 8 is a frame, 8a is a connecting portion, 8b is a constricted portion, 10 is a frame, 10b is a wiring insertion hole, 12 is a reduction gear unit, 13 is a bearing, 20 is an outer cable guide, 20a is a slide groove, 21 is an inner cable holder, and 21a is a slide protrusion.

Claims (2)

A frame of the second arm is rotatably connected to the frame of the first arm via a shaft portion, and is located on the outer peripheral side of the shaft portion and serves as a cable passage to the frame of the second arm. It is a joint structure of a robot in which a wiring insertion hole is provided,
The wiring insertion hole is formed in a long hole shape extending in the circumferential direction,
The cable is provided so as to be slidable in the circumferential direction inside the wiring insertion hole, and is in contact with the frame of the first arm according to relative rotation of the second arm with respect to the first arm. A joint structure of a robot, characterized in that it is provided in a state where it is held by a robot. The wiring insertion hole is provided with an outer cable guide formed in a cylindrical shape that is curved in an arc shape along a direction in which the wiring insertion hole extends from plastic, and the inner cable made of plastic is provided in the outer cable guide. 2. The joint structure of a robot according to claim 1, wherein the holder is slidably supported.

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