JPH0443753B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an industrial assembly robot.

In recent years, automation of assembly work has been rapidly progressing through the introduction of assembly robots in production processes. An example of a conventional assembly robot used for this purpose is shown in FIG.

This robot consists of two joints, a first arm 1 and a second arm 2, and a DC servo motor 3 is installed at the base of the first arm 1.
is provided to directly drive the first arm 1, and a DC servo motor 4 is provided at the base of the second arm 2 which is pivotally supported at the tip of the first arm to directly drive the second arm 2. .

An air cylinder 5 is provided at the tip of the second arm 2, and a hand 6 is attached to the tip of the piston rod.
It is moved up and down as the air cylinder 5 expands and contracts. Furthermore, the pulse motor 7 is fixed to the base 8,
The rotational force is transmitted to the hand 6 via the timing belts 9, 9', 9'' to perform the twisting action.

The above-mentioned robot (Fig. 1) has a first arm 1 and a second arm.
It has a total of four degrees of freedom: two degrees of freedom in the horizontal plane due to the arm 2, a degree of freedom in the vertical direction, and a degree of freedom in twisting the hands.

The conventional assembly robot described above has a drawback in that the rotational inertia of the rotating members is large. For this reason, it is difficult to increase the speed of the turning operation, and it is also difficult to improve stopping accuracy. Therefore, it is necessary to install a large capacity drive motor.

One of the reasons why the rotational inertia is so large is that the DC servo motor 4 is installed at the tip of the first arm 1.
The servo motor 4 must be swung around when the first arm 1 turns.
In an attempt to eliminate these shortcomings, the second
Relocating the rotation drive motor of arm 2 to a fixed member,
There are examples in which the second arm 2 and its rotation drive motor are linked with a connecting rod, but in this structure where power is transmitted between the crank and the connecting rod, it is difficult to control the rotation angle of the second arm.
It has to be much smaller than 180°, so
The second arm is restricted by a narrow range of motion. This is because if the rotation angle approaches 180 degrees, a point will occur at the end of the rotation stroke, making transmission impossible. If the movable range of the assembly robot is narrow, a large space is required to move the robot's hands, and when the robots are installed in a row, the installation interval must be widened. Furthermore, it is difficult to perform assembly work near the location where the robot is installed.

The present invention has been made to eliminate the drawbacks of the conventional devices described above, and its purpose is to be able to stop the vertical movement of the hand at a desired position with high precision, and to reduce the rotational inertia of the rotating part. To provide an assembly robot which can be operated at high speed with a small and small-capacity drive motor, can rotate the second arm more than 180 degrees with respect to the first arm, and has a wide movable range of the second arm.

In order to achieve the above object, the assembly robot of the present invention includes a first arm pivotally supported by a fixed member so as to be rotatable about a first shaft, and a first arm configured to drive the first arm.
a first drive motor provided on the same axis as the shaft; a second arm rotatably supported at the tip of the first arm by a second shaft parallel to the first shaft; It has a tool holding shaft supported at the tip of the second arm so as to be slidable in the axial direction parallel to the axis and rotatable around the axis, and the tool holding shaft is rotationally driven. In the assembly robot, the assembly robot is provided with a third motor that is coaxial with the first shaft and provided on the opposite side with the first arm in between so as to drive the second arm. a drive motor; and a double crank mechanism that transmits the power of a second drive motor provided on the axis of the first shaft to the second arm, the double crank mechanism comprising: an axis of the first shaft; The second crankshaft is parallel to the first crankshaft, and has a first crankshaft provided on the center as its center of rotation, and is parallel to the first crankshaft so as to produce a phase difference at a position equidistant from the axis of the first crankshaft. and third
a first crank that rotatably supports a crankshaft; and a first crank that is rotatably supported at one end by the second crankshaft.
a second crankshaft, one end of which is pivotally supported by the third crankshaft;
a fourth crankshaft that pivotally supports the other ends of the first and second connecting rods, and is provided on the axis of the second shaft so that both the connecting rods are always parallel. fifth and sixth crankshafts that are parallel, and the positional relationship of an isosceles triangle consisting of the fourth, fifth and sixth crankshafts with the first, second and third crankshafts; It is characterized in that it is constructed by forming crank portions on the second arm so as to correspond to each other.

Next, one embodiment of the present invention will be described with reference to FIGS. 2 to 5. Among the members constituting this embodiment, 42a is a central shaft as the first crankshaft, 42b is a crank pin as the second crankshaft, and 42c is the third crankshaft. 12a is a crank pin as the fourth crankshaft, 12b is a crankpin as the fifth crankshaft, and 12c is a crankpin as the sixth crankshaft. , 42 is a double crank as the above crank, and 52b and 52c are provided as the first and second connecting rods, respectively, and form a pair of double crank connecting rods.

FIG. 2 is a side view of an embodiment of the assembly robot according to the present invention, and FIG. 3 is a side view similarly cut at the center.

(See Figures 2 and 3), this robot is the first
It has a two-joint structure consisting of an arm 11 and a second arm 12.
The individual drive motors 21, 22, 23, and 24 are all installed on a post 20, which is a fixed member.

The first arm 11 is configured to be directly driven via a speed reducer 31 by a DC servo motor 21 installed concentrically with the pivot shaft thereof.

The second arm 12 transmits the output of a DC servo motor 22 concentrically to the pivot shaft of the first arm 11 to a reducer 32.
The configuration is such that the information is transmitted to the double crank 42 via the. As shown in FIG. 4, the double crank 42 described above is provided with two crank pins 42b and 42c having a phase difference of 90 degrees with respect to the central axis 42a. Correspondingly, two crank pins 12b and 12c having a phase difference of 90 degrees with respect to the second shaft 12a which pivotally supports the second arm 12 are also provided at the base of the second arm 12. And the same as the crank pin 42b mentioned above.
2b are connected by a connecting rod 52b, and the crank pin 42c and the crank pin 12c are connected by a connecting rod 52c.

(See Fig. 2) The outline of the hand mechanism is that a pair of upper and lower bases 64a, 64b are connected via a rack 62, and a pair of upper and lower bases 64a, 64b are connected together.
A book slide shaft 65 is rotatably supported in the following manner, and the hand 6 is attached to the lower end to form a tool holding shaft.

(See Figure 3) A pair of upper and lower bases 64a, 64
b have rotating brackets 64a _-1 and 64b _-1 , respectively.
is rotatably supported, and two slide shafts 6
5 and 65 are fixed to the rotating brackets 64a _-1 and 64b _-1 , respectively. Thereby, the two slide shafts 65, 65 are rotatably supported around the symmetry axis AB of these two slide shafts.

(See Figures 3 and 5) A sprocket 45 is rotatably supported at the tip of the second arm 12, and the two slide shafts 65, 65 are inserted into the two holes 45a, 45b bored in the sprocket 45. Penetrates freely. Thereby, the hand mechanism that supports the hand 6 is rotatably supported at the tip of the second arm 12. As will be described in detail below, this hand mechanism is configured to be twisted through a sprocket 45 and moved up and down through a rack 62.

(See Figures 2 and 3) A DC servo motor 24 is installed on the post 20, and its rotation is controlled by a reducer 3.
4. Transmission is transmitted via the sprocket 44 and chain 54 to the sprocket 45 provided at the tip of the second arm, which is rotated to cause the hand mechanism to perform a twisting action (FIG. 3). Transmission by the chain 54 is carried out by an idler sprocket 44', which is provided concentrically with the first shaft that supports the first arm 11.
The power is transmitted to the tip of the second arm 12 sequentially through the idler sprocket 44'', which is provided concentrically with the second shaft supporting the second arm 12.
Even when the arm 11 rotates around the first axis and the second arm 12 rotates around the second axis, the transmission by the chains 54' and 54'' is performed without any problem. This can be produced by using wrapped transmission means such as sprockets, or belts and pulleys, or wire ropes and drives.

(See Fig. 3) A DC servo motor 23 is installed on the post 20, which is a stationary member, and its rotational output is transmitted to the second-stage pulley 43' by the timing pulley 43 and the timing belt 53.
3' to transmit the deceleration to the timing belt 53', further decelerate by the two-stage pulley 43'', rotate the pulley 43 by the timing belt 53'', and the bevel gear 60a concentrically connected to the pulley 43. Configure to drive.

(See Figure 5) The rotation of the bevel gear 60a is caused by the bevel gear 6
0b, spur gear 61a, spur gear 61b, pinion 6
1c, and the pinion 61c drives the rack 62 up and down. 63,63
is a roller that guides the rack 62. As a result, the rack 62 is moved up and down, and the rack 62 is moved up and down.
The upper and lower bases 64a and 64b (see FIG. 2) fixed to the handle 2 are moved up and down to drive the hand 6 up and down. The vertical movement of the hand 6 is driven by the DC servo motor 23 via the rack 62 and pinion 61c, so it can be freely moved up and down.
And it can be stopped accurately at any position. Since the motor 23, which is a heavy member, is installed on the post 20, which is a fixed member, it does not increase the rotational inertia of the rotating member. Moreover, the transmission means from the motor 23 to the pinion 61c does not hinder the rotation of the first arm 11 and the second arm 12. Such an effect is achieved by transmitting the rotation of the motor installed on the fixed member to the hand mechanism through a winding transmission means, and driving the hand mechanism, which is a tool holding shaft, through a means for converting rotational motion into linear motion. caused by doing.
Any means such as a combination of a feed screw and a nut may be used as means for converting the above-mentioned rotational motion into linear motion.

(See FIG. 2) The DC servo motor 22 rotates the double crank 42. (See Fig. 4) The rotation of the double crank 42 is carried out through two transmission paths with a phase difference of 90 degrees, that is, the crank pin 42.
b, the second arm 12 is driven via the connecting rod 52b, the crank pin 12b, and the crank pin 42c, the connecting rod 52c, and the crank pin 12c. For this reason, the second arm 12 can be used over a wide range without creating any considerations unlike those in single crank means.
The rotation can be driven.

In this embodiment, rotational drive of approximately 300 degrees is possible.

Moreover, the double crank mechanism described above moves such that the crank pins 42b, 42c, 12c, 12b are always located at the vertices of the parallelogram. Therefore, when the first arm 11 is rotated while the double crank 42 remains stationary, the second arm 12 moves in parallel while drawing a circular arc along the second shaft 12a, which is the central support axis.

The second arm 12 moves in parallel as described above,
Furthermore, since the entire drive motor is installed on the post 20, the rotational inertia of the rotating portion of this robot is significantly smaller than that of conventional robots. Next, the principle will be explained with reference to FIGS. 6 and 7.

Figure 6 shows the first part of the conventional robot shown in Figure 1.
This is a schematic representation of the case where arm 1 rotates by an angle θ, where 2 is the second arm, m ₁ is the concentrated mass of the first arm 1,
m ₂ is the mass of the drive motor 4 of the second arm, m ₃ is the concentrated mass of the second arm 2, and m ₄ is the concentrated mass of the hand mechanism.
It is assumed that the lengths of the first arm 1 and the second arm 2 are both 2a.

When the first arm 1 is rotated by an angle θ, the second arm 2 is also rotated by an angle θ. Therefore, the rotational inertia J of the first arm 1 is J=m ₁ r ₁ ² +m ₂ r ₂ ² +m ₃ r ₃ ² +m ₄ r ₄ ² . However, r ₁ is the radius of rotation of m ₁ , r ₂ is the radius of rotation of m ₂ , r ₃ is the radius of rotation of m ₃ , and r ₄ is the radius of rotation of m ₄ .

FIG. 7 is a diagram schematically showing the case where the first arm 11 of the embodiment rotates by an angle θ.

As explained with reference to FIG. 4, when the first arm rotates by an angle θ, the assembly robot according to the present invention
The second arm moves in parallel while drawing an arcuate trajectory.
Therefore, the radius of rotation of the second arm is not the sum of the length of the first arm. Therefore, the load inertia J' of the first arm 11 is J'=(m ₁ +m ₅ )r ₁ ² +m ₃ r' ₃ ² +m ₄ r' ₄ ² . m ₅ is the mass of the link 10.

Here, both the lengths of the first arm 11 and the second arm 12 are
Comparing the load inertia J in Figure 6 and the load inertia J' in Figure 7 as 2a, J = m ₁ a ² + m ₂ (2a) ² + m ₃ (3a) ² + m ₄ (4a) ² ( m ₁ +4m ₂ +9m ₃ +16m ₄ ) a ² J′ = (m ₁ + m ₅ ) a ² + m ₃ a ² + m ₄ (2a) ² = (m ₁ + m ₃ + 4 m ₄ + m ₅ ) a ² and common sense in design Since it is considered that m ₂ > m ₅ , it is clear that J≫J′.

For example, m ₁ = 5Kg, m ₂ = 2Kg, m ₃ = 4Kg, m ₄
Assuming = 2Kg, m ₅ = 1Kg, 2a = 0.4m, the trial calculation results in J = 3.24Kgm ² and J' = 0.72Kgm ^2. By applying the present invention, the load inertia of the first arm is lower than that of the conventional one. This is approximately 1/5 of the robot.

As a result, when the present invention is applied, the capacity of the drive motor for the first arm can be made extremely small if the work speed is the same as that of the conventional one.
If the capacity of the arm drive motor is kept at the same level as before, the work speed will be significantly faster.

As explained above, the present invention includes a first arm pivotally supported by a fixed member so as to be rotatable about a first shaft;
A first drive motor is provided on the same axis as the first shaft to drive the first arm, and a shaft is provided at the tip of the first arm so as to be rotatable by a second shaft parallel to the first shaft. It has a supported second arm, and a tool holding shaft supported at the tip of the second arm so as to be slidable in an axial direction parallel to the second axis and rotatable around the axis, and an assembly robot comprising a third motor for rotationally driving the tool holding shaft, the third motor being coaxial with the first shaft to drive the second arm, and sandwiching the first arm a second drive motor provided on the opposite side of the first shaft, and a double crank mechanism that transmits power of the second drive motor provided on the axis of the first shaft to the second arm, and The double crank mechanism rotates around a first crankshaft provided on the axial center of the first shaft, is parallel to the first crankshaft, and is rotated from the axial center of the first crankshaft. The second and third
a first crank that rotatably supports a crankshaft; and a first crank that is rotatably supported at one end by the second crankshaft.
a second crankshaft, one end of which is pivotally supported by the third crankshaft;
a fourth crankshaft that pivotally supports the other ends of the first and second connecting rods, and is provided on the axis of the second shaft so that both the connecting rods are always parallel. fifth and sixth crankshafts that are parallel, and the positional relationship of an isosceles triangle consisting of the fourth, fifth and sixth crankshafts with the first, second and third crankshafts; Since crank portions are formed in the second arms to correspond to each other, the movable range of the robot can be increased, and the rotational inertia of the rotating arms can be reduced.

As mentioned above, the possible range of robots has become wider (more specifically, the range of motion of the second arm has become wider than that of the first arm), and the interval between robots installed in rows has become narrower. This makes it possible to save space.

Furthermore, if the movable range of the second arm relative to the first arm is wide, a practical effect can be obtained in that assembly work can be safely performed near the location where the robot is installed.

[Brief explanation of drawings]

FIG. 1 is a front view of a conventional two-joint type assembly robot, and FIGS. 2 to 5 show an assembly robot according to an embodiment of the present invention. The figure is a front sectional view cut at the center.
FIG. 4 is a plan view of the double link portion, and FIG. 5 is a cutaway plan view of the tool holding and rolling drive portion. FIG. 6 is a schematic diagram showing a link mechanism of a conventional assembly robot, and FIG. 7 is a schematic diagram showing a link mechanism of a robot according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 11...First arm, 12...Second arm, 20...Post as a fixing member, 21, 22, 23, 24
... Drive motor, 42 ... Double crank, 52
b, 52c...Connecting rod of double crank mechanism, 5
3...Belt, 54...Chain, 60a, 60
b...Bevel gear, 61a, 61b...Spur gear, 61
c...pinion as a means for converting rotational motion into linear motion, 62...also a rack, 65...slide shaft as a tool holding shaft.

Claims (1)

[Scope of Claims] 1. A first arm pivotally supported by a fixed member so as to be rotatable by a first shaft, and a first arm provided on the same axis as the first shaft so as to drive the first arm. a first drive motor; a second arm pivotally supported at the tip of the first arm so as to be rotatable by a second shaft parallel to the first shaft; and a second arm sliding in the axial direction parallel to the second shaft. and a tool holding shaft rotatably supported at the tip of the second arm about the axis, and a third motor for rotationally driving the tool holding shaft. In the robot, a second drive motor coaxial with the first shaft and provided on the opposite side of the first arm to drive the second arm; and an axis of the first shaft. a double crank mechanism that transmits the power of a second drive motor provided on the center to the second arm, the double crank mechanism including: a first crank provided on the axis of the first shaft; The second and third crankshafts are parallel to the first crankshaft and have a phase difference at positions equidistant from the axis of the first crankshaft.
a first crank that rotatably supports a crankshaft; and a first crank that is rotatably supported at one end by the second crankshaft.
a second crankshaft, one end of which is pivotally supported by the third crankshaft;
a fourth crankshaft that pivotally supports the other ends of the first and second connecting rods, and is provided on the axis of the second shaft so that both the connecting rods are always parallel. a fifth and a sixth crankshaft that are parallel; The second
An assembly robot characterized in that it is constructed by forming a crank part in its arm. 2. The assembly robot according to claim 1, wherein the second and third crankshafts have a phase difference of approximately 90 degrees with respect to the first crankshaft. .