JPH0265988A - Transmission device for power of robot - Google Patents

Abstract

PURPOSE:To almost neglect the adverse effect due to the chattering of proper links to a double link mechanism by fitting a terminal arm to a terminal arm axis so that the axial line of the terminal arm becomes about in parallel to the axial line of a base part arm in case of two links being superposed. CONSTITUTION:Both ends of two links are pivotally supported by bearings so that the phase difference of two links becomes at 90 deg. and the turning faces of two links vary each other by a pair of the two sets of columns whose distances from the respective rotary center are equally provided on a 1st link plate member and 2nd link plate member in the length equal to the interaxial distance of a driving axis and terminal arm axis. A terminal arm 10 is fitted to a terminal arm axis so that the axial line of the terminal arm 10 becomes about parallel to the axial line of the base part arm 5 in case of two links being superposed each other. Consequently, the adverse effect due to the chattering of the proper links to a double link mechanism can be neglected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a power transmission device for a robot having rotating joints.

(Conventional technique) Conventionally, in articulated robots, the moment of inertia of the arm has been reduced in order to improve the robot's motion performance.
As shown in FIG. 4, a double link mechanism is known as a power transmission mechanism between the output shaft Al' of the motor A1 and the drive shaft A2. This link plate A3. A4 has a length equal to the distance between the output shaft Al' and the drive shaft A2.
Book link A5. Two sets of pins that supported A6 are 90
It is fixed with a phase difference of degrees. In addition, as an example of a double link mechanism, Utility Model Publication No. 63-4632,
There are Japanese Patent Laid-Open No. 63-77674, etc.

(Problem to be Solved by the Invention) According to the double link mechanism described above, a rotation range of 270 degrees or more can be obtained, but the double link does not reach the state shown in Fig. 15, that is, the state in which the two links overlap. When this happens, "wobbly" may occur, where the link becomes loose.

By the way, the torque transmission of the link mechanism is shown in FIG. 16 (for convenience of explanation, only one link is used).

Crank C1 and link C connected to the output shaft of the motor
The torque of the motor is transmitted to the second connecting shaft support C3 in the tangential direction of rotation of the crank C1. At this time α
is the angle formed by the base arm C4 and the crank C5.

On the other hand, a force F acts on the crank C5 connected to the tip arm C6 and the connecting shaft support C7 at the other end of the link C2 in the direction tangential to the rotation thereof.

At this time, part of the force generated at both ends of link A and link B in FIG. 9 becomes as shown in FIG. 17. In Figure 15, if the angle between link A and the extension line D3 of the base arm is α, and the angle between link B and the extension line D3 of the base arm is α, then α = 135° (α' = 45°). Sometimes the directions of links A and B match.

If this point is named a "force inflection point", the magnitude of the force acting in the axial direction of the link A and link B (the axial support at both ends of the link) is changed at this force inflection point.

Incidentally, in an actual mechanism, a rolling bearing such as a ball bearing is used for each shaft support of the link, and the rolling elements (balls) are elastically deformed by the force applied to the bearing.

Since the forces acting in the axial direction of the two links at the above-mentioned inflection point are reversed, the amount of elastic deformation of the rolling bearing of each link shaft support is also reversed, and this appears as the above-mentioned "wobble".

In addition, there are other inflection points other than the angles shown in Figure 15, but at other inflection points, the forces acting in the axial direction of the two links are opposite, so the angle at which the amount of elastic deformation of the rolling bearing is present is There is no sudden reversal at the (inflection point), so there is no "wobble".

(Means for Solving the Problems) The present invention aims to solve the above-mentioned problems by fixing a drive shaft connected to a motor to a first link plate member disposed at the rear of the base arm, and A tip arm shaft is pivotally supported in parallel to the active shaft via a bearing in the front part of the arm, a second link plate member is fixed to the tip arm shaft, and the distance between the active shaft and the tip arm shaft is equal to the distance between the axes. In terms of length, the phase difference between the two links is approximately 9 degrees due to the two sets of pillars provided at both ends of the two links on the first link plate member and the second link plate member at equal distances from the center of rotation. to the degree,
In addition, the two links are supported by bearings so that their rotational surfaces are different from each other, and the tip arm is supported so that when the two links overlap, the axis of the tip arm becomes approximately parallel to the axis of the base arm. It is characterized by being attached to the tip arm shaft.

(Structure) A detailed description will be given below based on the illustrated embodiment. A flange 2 is fixed to the upper part of a fixed base 1. The fixed base 1 has a direct drive (hereinafter referred to as DD) for driving the base arm.
A stator portion 3a of the motor 3 is fixed. The D
A spacer 4 is fixed to the upper part of the rotor of the D momo-3, and a rear (base) part 5a of a base arm 5 is fixed to the spacer 4.

On the other hand, on the opposite side of the base arm 5 tip 5b from the base arm drive DD motor 3, a support member 6 has an elongated hole so that its position can be adjusted in the longitudinal direction of the arm in a direction perpendicular to the output shaft of the base arm drive DD motor 3. The base arm 5 is fastened to the base arm 5 by bolts. A cross roller bearing 8 is fixed to the support member 6 by a presser plate 7, and the cross roller bearing 8 connects the tip arm shaft 9 to the base arm drive D.
It is supported in parallel with the output shaft of D motor 3. 10 is a tip arm connected to the tip arm shaft at its rear.

Further, a distal arm drive shaft 11 is coaxially supported on the spacer 4 by bearings 12a and 12b, coaxially with the output shaft of a DD motor for driving the base arm. A first link plate 13 is connected to the protruding end of the distal arm moving shaft 11 in the base arm 5 by fitting a fitting hole 13a into the fitting shaft 11a of the distal arm moving shaft 11. In addition, the tip arm shaft 9
A second link plate 14 is also connected to the base arm 5 side by fitting the fitting hole 14a to the fitting shaft 9a of the distal arm shaft 9. Fitting holes 15, 16° and 17.18 are bored in each of the facing surfaces of the first link plate 13 and the second link plate 14 at distances r, r2, r, and r2' from the center of rotation of the link plate. It is being This fitting hole 15° 16, 17, 18 and the fitting hole 13a, 1
4a is the first link plate 13 and the second link plate 1
4 are manufactured by simultaneous machining, so the distance from the center of rotation for each is r machining = r machining', r2''r2'
+ Also, the angle α=β. A pair of link shafts 15 with different lengths are provided in the fitting holes 15, 16 and 17.18, respectively.
a, 16a, 17a, and 18a are the tip arm sleeping shafts 1
It is installed parallel to 1.

Long link shaft 15a, short link shaft 17a, short link shaft 16
a and the long link shaft 18a are bearings 19a, 20a, 19b.
, 20b, 19c, 20c, 19d, 20d by links 21.22, respectively. Link 21 and link 22 are connected to link plate 13-. The rotating surfaces are different so that there is no interference even when 14 rotates.

Further, the links 21 and 22 have the same center distance lie□le2 due to simultaneous machining. Also el,
The design dimension of e2 is set equal to the distance between the axes of the base arm 5.

In addition, each of the links 21 and 22 has a disc spring 23 and 24 inserted between two bearings, and a presser plate 25.
A preload is set to eliminate the radial clearance of the bearing across the outer ring of the bearing, the ball, the inner ring of the bearing, the disc spring, the inner ring of the bearing, the ball, and the outer ring of the bearing. 26 is presser plate 2
5 to the links 21 and 22.

The shaft supports at both ends of each link 21 and 22 are preloaded to eliminate the radial clearance of the bearing, as shown in FIG. 7, and at least one shaft support is aligned with the link shaft for axial alignment. The link (bearing inner ring) is movable in the axial direction.

Note that 27 and 28 are lids attached to the base arm 5 and used during assembly.

Further, the diameters of the fitting holes 13a and 14a, 15a and 17a, 16a and 18a, and the bearing holes of the links 21 and 22 are the same.

On the other hand, inside the fixed base 1, a stator 27a of a DD motor 27 for driving the tip arm is fixed to the bottom 1a of the fixed base 1. The output shaft (rotor) 27b of the tip arm drive DD motor 27 is connected to the tip arm active shaft 11.
It is installed so that it is coaxial with the D for tip arm drive
The output shaft 27b of the D motor 27 is the tip arm beating shaft 11.
It is fastened to a flange 28 connected to the lower end 11b of.

A gap is provided between the flange 28 and the flange 2. Further, a hollow shaft portion 4a is formed in the lower part of the spacer 4 and passes through between the hollow portion 3d of the base arm drive DD motor 3 and the tip arm drive shaft 11,
A downwardly protruding portion 4a of the flange 2 of the hollow shaft portion 4a
' A block 30 is connected within the gap. The block 30 is pivotally supported by the flange 28 via a bearing 32. 23 and 24 are disc springs that apply preload to the bearing 32.

A mechanical stopper for restricting rotation of the base arm is formed on the block 30 and comes into contact with a fixed stopper 33 fixed to the flange 2. Further, the block 30 is provided with a dog 34, and the flange 2
The origin is fixed to the bracket 1-35 provided in the base arm for detecting the rotation angle of the base arm, and the proximity switches 36, 37, and 38 for overrun detection are used to detect the rotation angle of the base arm. A relay box 40 having a connector 39 connected to a controller (not shown) is provided on the back side of the fixed base 1.

Furthermore, a support column 41 for wiring is attached to the upper surface of the fixing table between the relay box 4o and the flange 2. A flexible conduit tube (hereinafter referred to as a conduit tube) 4 is connected to the upper end of the wiring support 41 via a rotary connector 42.
One end of 3 is connected.

The other end of the conduit tube 43 is provided at the rear upper part of the distal arm 10 so as to be approximately coaxial with the distal arm shaft 9, and is connected to the distal arm 10 via a rotary connector 45 provided on the upper part of the cover 44. ing.

Inside the tip arm 1o, an AC motor 47 for driving the rotation of the work shaft and an AC motor 48 for driving the work shaft positioning stopper are provided on the parallel tip arm shaft 9, including a reduction gear 46. The AC motor 47 is provided to be substantially coaxial with the tip arm shaft 9, and a timing pulley 48 is connected to the output shaft 46a of the reducer 46, and a timing pulley 49 is connected to the output shaft 48a of the AC motor 48, which will be described later. are doing.

On the other hand, the front part 10b of the tip arm 10 has spline bearings 51, 51' so that a pair of working axes 50°50' formed by splines are parallel to the tip arm axis 9.
, 52.52', radial bearing 53.53', 54
．． 54', it is pivotally supported so as to be movable and rotatable in the axial direction.

The spline bearings 51.51' and 52.52' are connected to the timing pulley 56 via sleeves 55.55'.
．． 56'. The timing pulley 56
．． 56' and the timing pulley 48 are rotationally connected by a timing belt 57.

Further, the upper end portions 50a, 50a' of one working shaft 50.50' are the rods 5 of a pair of air cylinders 58.58' provided at the upper front part of the tip arm 10 in parallel with the working shaft 50.50'.
Joint 59.59' connected to 8a, 58a'
The bearings 60, 60' are provided so as to be rotatable and integral in the axial direction.

On the other hand, a sleeve 63 is rotatably supported in parallel to the working shaft 50.50' through bearings 61 and 62 at the intermediate portion of the working shaft 50.50' at the front of the tip arm 10. A timing pulley 64 is formed on the sleeve 63 above the bearing 61, and is rotatably connected to the timing pulley 49 by a timing belt 65, and a sliding stopper 6 having a thread formed on the outer periphery is attached above the timing pulley 64.
A bearing 67 having a female thread that fits into the male thread of No. 6 is fixed. Reference numeral 68 denotes a stopper portion formed on the top of the sliding stopper 66, and is guided in a slidable but non-rotatable manner by a guide 69 fixed inside the distal arm 10 in parallel to the axis of the sleeve 63. Reference numeral 70 is a cover provided at the front part of the tip arm 10.

Note that the cover 70, cover 44, relay box 40, lids 27, 28, support member 6, etc. have a structure that seals the inside of the robot from the outside.

70, 71, and 71' are proximity switches for origin and overrun detection for detecting the rotation angle of the tip arm.

Further, 72 is a mechanical stopper for the tip arm fixed to the rear part 5a of the base arm 5, and is adapted to come into contact with the first link plate when the tip arm overruns.

In the present invention, a mechanical stopper 72 for the tip arm and a mechanical stopper 33 for the base arm are provided inside the robot. Therefore, safety is improved, and even if the robot overruns and contacts the mechanical stopper, the dust generated by the contact will not be released to the outside, so it can be used in environments that require cleanliness.

Although a block 30 with a mechanical stopper and a fixed stopper 33 were provided in the gap between the flange 2 and the flange 28, a D for driving the tip arm was provided instead of the stopper.
A brake for stopping the rotation of the output shaft 27b of the D motor 27 and the hollow shaft portion 4a may be provided on the flange 2 or the fixed base. Moreover, in this case, one brake means can simultaneously control the output shaft 2 of the DD motor for driving the tip arm.
7b and the hollow shaft portion 4a may be stopped.

Note that a work tool (not shown) is attached to the lower ends 50b, 50b' of the work shafts 50, 50'.

Further, 73 is a cable that is inserted into the conduit tube 43 and connects the relay box 40 and the distal arm 10. Since no electrical components are installed inside the base arm 5, there is no risk of cable breakage even if the links 21 and 22 rotate.

Also, the lids 27 and 28 are located at the rear of the base arm 5 (
These two holes are provided to seal the holes formed in the upper part of the base part and the lower part of the front (tip) part, but these two holes are working holes for assembling the links 21, 22, etc. into the base arm 5. However, since the base arm has a closed structure except for this hole and the pivot point facing the hole, high arm rigidity can be obtained (usually, an arm with a built-in link has a structure in which one side of the arm is completely closed). The rigidity was low because it became .

).

Further, an exhaust tube may be provided in the conduit tube 43 to suck in dust generated inside the robot from the outside. Since the conduit tube 43 is connected at one end to the approximate center of rotation of the distal arm 1o by a rotary connector, it can easily follow the fast movement of the arm (conventionally, the resistance caused by bending or twisting of the wiring attached to the arm (There was a problem with accuracy deterioration due to this.)

In addition, since the tip arm shaft 9 is supported by the cross roller bearing 8, the thickness of the shaft support becomes thinner, and the base arm 5
There is no longer a protrusion on the top of the tip. For this reason, a heavy AC motor 47.4 is installed inside the base of the tip arm 10.
8 can be arranged, it is possible to reduce the moment of inertia of the distal arm, and at the same time, it is possible to secure the space necessary for the double link mechanism within the base arm 5.

(Function) In Figures 12 to 16, A is the robot base, mouth, C, 2, and Ho are cranks (actually link plates) that connect the links 21 and 22 and each axis, respectively, and H is the tip of the tip arm 10. This is the load provided. H is the axis of the base arm 5.

The distal arm 10 rotates to the right every time from FIG. 8 to FIG. 12.

Let α and α' be the angles formed by the axis C of the base arm 5 and the crankshaft and C, respectively.
5°), Fig. 10 (α = 135° α' = 45')
, an inflection point occurs in FIG. 11 (α=225°, α'=135°).

As mentioned above, the inflection point in Figures 9 and 11 is link 2.
1.22 Since the direction of the force acting on the link is opposite, "wobble" does not occur in the link. In the case of FIG. 10, since the tip arm 10 is parallel to the base arm 5 (on the same straight line), it appears only in the arc Q of the working range outline shown in FIG. Since this portion of the arc Q is extremely rarely used as a working range of the robot, the adverse effect on accuracy due to "wobble" of the link at this point can be almost ignored.

(Effects) As described above, the present invention provides the first
A drive shaft connected to a motor is fixed to the link plate member, a tip arm shaft is pivotally supported in parallel to the drive shaft via a bearing in the front part of the base arm, and a second link plate member is attached to the tip arm shaft. As well as being fixed,
With a length equal to the distance between the drive shaft and the tip arm shaft, both ends of the two links are attached to the first link plate member and the second link plate member, respectively, with a pair of links provided at equal distances from the center of rotation. The two links are supported by bearings using two sets of struts so that the phase difference between the two links is approximately 90 degrees, and the rotation surfaces of the two links are different from each other.
The feature is that the tip arm is attached to the tip arm axis so that when the two links overlap, the axis of the tip arm becomes approximately parallel to the axis of the base arm. This has the effect that the adverse effects caused by "rattling" can be almost ignored.

Although the present invention uses a direct drive motor as the active source, other rotary actuators may be used instead.

In addition, as for the structure of the link plate part, in addition to the one-piece structure as in the present invention, the structure of the link plate part is as follows:
It is also possible to use a plurality of types as shown in No. 3-77674.

Furthermore, considering the position shown in FIG. 14 as the neutral point of the double link mechanism, there is also the effect that the largest working range can be obtained symmetrically from this position.

[Brief explanation of the drawing]

Fig. 1 is a front sectional view of an embodiment of the present invention, Figs. 2 and 3 are enlarged views of the main parts of Fig. 1, Fig. 4 is an external if side view of Fig. 1, and Fig. 5 is the same plane. Figure 6 is a plan view of the link in Figure 1, Figure 7 is a front sectional view of the shaft support of the link in Figure 6, Figure 8 is an external perspective view of the conventional double link mechanism, and Figure 9 is Figure 8 is a plan view of the double links in a superimposed state, Figure 10 is the 8th
FIG. 11 is a diagram showing the force generated at both ends of link A and link B in FIG. Operation explanatory diagram. FIG. 17 is an explanatory diagram of the working range of the distal arm and base arm of the present invention. 1... Fixed base 3... Direct motor for driving base arm 5...
Base arm 9...Tip arm shaft 10...Tip arm 11...Tip arm drive shaft 13...First link plate 14...Second link plate 21.22...Link 27... Direct motor 27b for driving the tip arm
...Output shaft A...Robot base opening, C, 2, H...To the crank (link plate) that connects links 21 and 22 to each axis...Load on the tip of the tip arm Fig. 6

Claims (1)

[Claims] A drive shaft connected to a motor is fixed to a first link plate member disposed at the rear of the base arm, and a tip arm shaft is supported parallel to the drive shaft via a bearing at the front of the base arm. While fixing the second link plate member to the arm shaft, both ends of the two links are rotated into the first link plate member and the second link plate member, respectively, by a length equal to the distance between the drive shaft and the tip arm shaft. The two links are supported by a bearing so that the phase difference between the two links is approximately 90 degrees, and the rotation surfaces of the two links are different from each other. In addition, the robot power transmission device is characterized in that the tip arm is attached to the tip arm shaft so that the axis of the tip arm becomes substantially parallel to the axis of the base arm when the two links overlap.