JPS6361155B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gravity balance mechanism that stops a second arm of an articulated industrial robot, which is rotatably supported back and forth on a swivel table, at an arbitrary position against gravity. be.

a swivel table placed on the base; a second arm supported by a fulcrum provided at the bottom of the swivel table so as to be rotatable; and one end of the second arm rotatably mounted on the top of the second arm A so-called articulated robot, which is equipped with a first arm that is pivoted and has a wrist at the other end, will cause the gravity balance to become unbalanced when the second arm is tilted forward and backward, stopped at an arbitrary position, and the power is turned off. Because it is curved, it moves to the end of the stroke. In order to prevent this drawback, various gravity balance mechanisms have been provided in the past. Conventional typical balance mechanisms used a helical spring system for compression or tension along the arm, but this required two sets, one for forward tilting and one for rearward tilting, and had the disadvantage of requiring a large device. Ta.

The purpose of the present application is to achieve a balance between forward and backward tilting of the second arm (hereinafter simply referred to as the "second arm") supported on the above-mentioned swivel table so as to be rotatable back and forth. A mechanism structure is used in which the arm is balanced by a gear mechanism and a notch braking mechanism using two torsion springs, and the arm variation angle is expanded several times in terms of the number of teeth to achieve perfect balance.

An embodiment of the present invention will be described below with reference to the drawings.

As shown in the overall view of FIG. 1, a swivel table 2 that can freely rotate left and right is placed on a main body 1 that is fixed to the floor. As is well known, a second arm 3 that can be tilted back and forth is pivotally attached to the swivel base 2, and a first arm 4 that can be bent vertically is pivotally attached to the other end of the second arm. A wrist 5 is attached to the tip of this first arm 4,
Power mechanisms 6, 7, 8 are provided to control the respective movements. A drive gear 9 that transmits the varying gravity of forward and backward tilting applied to the second arm 3, which must be balanced, is incorporated into the joint shaft 10 of the second arm and is fixed to the second arm 3. Further, the driving gear 9 is a shaft 3 mounted on a spring box 14 fixed to the swivel base 2 so as to be easily replaceable.
It meshes with a passive gear 12 provided in a spring box 14 via an intermediate gear 11 rotatably fitted in the spring box 7 . The details of the mechanism for transmitting the torsion moment load to the torsion spring 13 will now be explained with reference to FIGS. 2 to 5. In FIG. 2, a driven gear 12 is fixed to the front end of a shaft 15 rotatably incorporated into the spring box 14, and a flange 16 is fixed to the right end. Note that the drive gear 9 and the passive gear 12
The structure is such that the turning angle can be expanded to several times the longitudinal inclination angle of the second arm 3 by the ratio of the number of teeth. Rotation limiting grooves 17 and 18 are provided on opposing sides of the driven gear 12 and the flange 16, respectively, and turners 19 and 20 are engaged with each groove. A worm shaft bracket 21 is fixed to the rotary ring 19, a rotatable worm 22 is built into the bracket, and a worm wheel 2 is fixed to the left end of the torsion spring 13.
3, the operator can adjust the spring force of the torsion spring 13 by rotating the worm 22 and the worm wheel 23.
The right end is fixed to the rotary ring 20. Note that the rotary wheels 19 and 20 are provided with protrusions 24 and 25, respectively, and stoppers 26 and 2 protruding into the spring box 14 are provided.
7 are provided, one each on the left and right. Further, flat bearings 34, 35, 36 are incorporated in the rotary wheels 19, 20 and the worm wheel 23, respectively, and are slidably fitted to the shaft 15.

The device of the invention operates as follows. When the second arm 3 is tilted forward 28, the drive gear 9 rotates in the direction of the front arrow 30 about the axis of the joint shaft 10.
This rotation angle is determined by the intermediate gear 11 and the passive gear 12.
is transmitted to. However, the driving gear 9 and the passive gear 1
2, the driven gear 12 operates with an enlarged rotation angle. At this time, the protrusion 25 of the rotary ring 20 hits the stopper 26 to prevent rotation. On the other hand, the rotation limiting groove 1 provided in the passive gear 12
The end face 32 of 7 rotates the rotor 19 in the direction of the forward arrow 30. Naturally, since the worm 22 and the worm wheel 23 are rotated together in the direction of the forward arrow 30, a reaction force rotation moment _F1 is generated in the torsion spring 13, and a forward weight rotation moment F1 is applied to the second arm 3. Balance with ₂ . In addition, if the second arm 3 falls in the backward 29 direction, the rear arrow 3
The passive gear 12 rotates in one direction. In this case, the protrusion 24 of the rotary ring 19 hits the stopper 27, and the rotary ring 19, the worm 22, and the worm wheel 2
Prevent rotation of 3. Therefore, the end face 33 of the rotation limiting groove 18 provided in the flange 16 rotates the rotary ring 20 in the direction of the rear arrow 31, so that a reaction force rotation moment F ₃ is generated in the torsion spring 15 and the second arm 3 is rotated. It always balances the applied rearward variable weight rotational moment F ₄ . Expressing this in formulas, F ₁ =F ₂ and F ₃ =F ₄ . In addition, the rotating money 19
The position adjustment between and 20 is performed by a worm 22 and a worm wheel 23.

As described _above , according to the present invention, only ₁
With a simple mechanism using four torsion springs 13, forward and backward reaction force rotation moments F ₁ ,
F ₃ can be generated and perfectly balanced, and the entire device is compact. Note that fine position adjustment is possible by using a worm and a worm wheel as position adjustment members, and by recombining the intermediate gear 11, the relative positions of the driving gear 9 and the driven gear 12 can be easily matched, which is a remarkable feature. It is effective.

[Brief explanation of drawings]

Figure 1 is an external view of the embodiment, Figure 2 is A of Figure 1.
-A sectional view, FIG. 3 is a BB sectional view in FIG. 2, FIG. 4 is a CC sectional view in FIG. 2, and FIG. 5 is a DD sectional view in FIG. 9... Drive gear, 10... Joint shaft of second arm, 11... Intermediate gear, 12... Passive gear, 13
...Torsion spring, 15...Shaft, 16...Flange, 17, 18...Rotation limiting groove, 19,20...
Turner, 22...worm (spring force adjustment member),
23... Worm wheel (spring force adjustment member),
37... Axis.

Claims (1)

[Scope of Claims] 1. In a balance mechanism for the fluctuating gravity caused by the back and forth tilting of a second arm which is pivotably mounted on the swivel table of an articulated industrial robot so as to be rotatable in the back and forth direction, a drive gear 9 that transmits variable gravity, which is incorporated in the joint shaft and fixed to the second arm;
A passive gear 12 meshes with the drive gear 9 through an intermediate gear 11 rotatably attached to a spring box fixed to a swivel base, and has a rotation limiting groove 17 on its side surface having a drive end surface 32, and a front and rear passive gear. Spring force adjusting members 22, 2 that transmit the rotation of the rotary rotary wheel 19 that is in contact with the end face and rotates in one direction and can transmit only gravity.
a torsion spring 13 on which a torsional moment load is accumulated from one end via a flange 1 fixed to a shaft 15 transmitting rotational gravity from the passive gear 12, and provided with a rotation limiting groove on one side having a driving end surface.
6, and a rotary ring 20 which is in contact with the flange 16 and is capable of transmitting gravity in the opposite direction to accumulate a torsion moment load on the torsion spring 13 from the other end of the torsion spring 13. 2. A gravity balance mechanism for an articulated industrial robot according to claim 1, wherein the intermediate gear 11 is incorporated into a shaft 37 that is easily recombinable. 3. The spring force adjusting member of the rotary rotary 19 for the torsion spring that transmits gravity from the rotary rotary 19 to the torsion spring 13 is composed of a worm 22 and a worm wheel 23. balance mechanism.