JPS59187490A - Automatic compensator in direction of sheave - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for automatically correcting the sheave surface direction of a rotating sheave used in a wire turn portion for a gravity balance device in accordance with the direction of a swinging wire. .

For example, in the case of an industrial robot used for painting, welding layers, etc., as shown in FIG. 3, and a horizontal arm 4 that is swingable in the vertical plane is attached to the tip of this vertical arm 3,
It generally has a so-called vertical structure in which a wrist portion 5 for attaching a tool or the like is provided at the tip of a vertical arm 4 of the saw. In such a vertical arm mechanism, since the horizontal arm 4 is given only the degree of freedom in the vertical direction, the movement of the arm in the vertical direction is restricted, but the movement in the horizontal plane is limited. The degree of freedom of work is often restricted for work objects for which there is relative freedom. Examples of work objects that have a relatively high degree of freedom in the lateral direction, but have limited movement in the vertical direction, include the processing of water turbine runners, marine propellers, turbine plates, etc., and the painting of automobile interiors. For work targets such as this, where the direction in which the arm mechanism can reach into a narrow space is restricted, a vertical multi-joint arm mechanism is used. Therefore, the present inventors invented a horizontal multi-joint arm mechanism in which the degree of freedom in the horizontal direction is increased by laying down the arm qB corresponding to the vertical arm 3 laterally. Already applied for (Patent Application 1986-6380)
issue).

In the case of such a horizontal multi-joint arm mechanism, the vehicle force of the entire arm has to act on the base of the arm mechanism, so the arm has a structure to eliminate such rotational moment. A gravity balance mechanism is required to suspend the arm so that it does not rotate using a wire attached to the middle of the arm, and this gravity balance mechanism must be able to expand and contract the length of the wire in response to the swinging motion of the arm. To prevent this, the wire is partially bent at the sheave surface so that it can be wound around the tension device, but with this type of mechanism, when the arm swings or turns, the wire position changes, and the wire is bent at the sheave surface. The disadvantage is that the wire can come off the sheave if it is fixed.

Such a drawback is not limited to the horizontal multi-joint mechanism as described above, but always occurs when it is necessary to bend the wire at the sheave surface and swing the wire, and the present invention solves this problem. In order to solve this problem, the rotary sheave is mounted so that it is rotated around an axis so that the sheave surface of the rotary sheave matches the direction of the wire according to the swing angle of the wire. The first shaft is rotatably attached to the base, and the end of the first shaft has a swingable shaft f1.
A first arm attached to the first arm, a rotating sheave attached to the base, and a wire connected to the first arm at -θ111, the other end of which is connected to the tension device through the same as above of the rotating sheave. In a device for balancing the gravity applied to the first arm, the device comprises: - detecting the position of a wire that swings around a sheave for 10 revolutions in response to the swing of the first arm: 1 yen; a detector, and in response to a signal from the position detector, rotates the rotating soap in the direction of swing of the wire.
There is also a point that the sheave drive device is included.

Next, seven embodiments in which the present invention is applied to the horizontal multi-joint arm mechanism will be described to provide an understanding of the present invention. Here, Fig. 2 is a q-main view of the entire horizontal multi-jointed arm mechanism, and Fig. 3 is a
The circle is a schematic configuration diagram showing the operating principle of the balance device for eliminating the rotational moment around the first axis of the entire arm mechanism shown in FIG. 2, and FIG. FIG. 5 is a front view including a partial cross section of the entire automatic correction device, and FIG. 5 is an enlarged view of a portion viewed from arrow A in FIG. 4.

Next, the entire horizontal multi-joint arm mechanism will be briefly explained.

In FIG. 2, the base 29 that supports the first shaft 11 so as to be able to rotate in the horizontal direction by means of a bearing 28 is connected to a horizontal pedestal 30.
The vertical base 32 is supported on the upper surface 31 so as to be slidable in the vertical direction along the vertical side surface 33 of the horizontal base 30, so that the vertical base 32 can be slidably supported in the horizontal and vertical directions. can be freely positioned against. A fulcrum 35 provided at the tip of an arm 34 fixed to the first shaft 11 and a base 2
9''- is connected to the fulcrum 36 by a first positioning means A that is swingably attached to both fulcrums. This first positioning means A and the second and third positioning means B and C described above are each constituted by a hydraulic cylinder, a ball screw, or other actuator or motor that can be expanded and contracted and whose expansion and contraction amount is precisely controlled. ing. Therefore, as the first positioning means A expands and contracts, the first shaft 11 turns by an arbitrary turning angle, and the first arm and second arm connected thereto turn as a whole around the first shaft 11 in the direction θ1. do.

The arm base 37 is fixed to the end of the first shaft 11 at a certain angle with respect to the first shaft 11, and the arm base 37 has a support shaft that is perpendicular to the first shaft 11 as described above. 12 is rotatably attached. The end of the first arm 13, which is capable of swinging about the support shaft 12, is fixed to the support shaft 12, and the other end of the first arm 13, which is rotatable and capable of swinging around the support shaft 12, is fixed to the support shaft 12. A fulcrum 21 provided at the tip of a link 20 swingably attached to a support shaft 14 attached parallel to the arm base 37 and a fulcrum 18 fixed to the arm base 37 The line segment connecting the fulcrum 18 and the intersection 23 of the axis of the support shaft 12 and the axis of the first shaft 11 is parallel to the first link 20, and the link 22 and the A parallel link is formed such that the first arm 13 is parallel to the first arm 13. Further, a fulcrum 17 provided in the middle of the first link 13 and an arm base 3
7 is connected to the fulcrum 16 by a second positioning means I3 made of a pole screw or the like as described above,
The first arm 13 is
swings about the first shaft 11.

A second arm 15 is attached to the tip of the first arm 13 and is swingable about the support shaft 14 which is rotatably attached to the first arm. A built-in third positioning means C (not shown), which is made of a pole screw or the like, connects an intermediate fulcrum (not shown) of the second arm 15 and a fulcrum (not shown) whose position is fixed relative to the first link 20. The second arm 15 swings in the direction of θ3 within the first plane including the first shaft 11 and the first arm 13 due to the expansion and contraction operation of the third positioning means C. Because the angle of the link 20 is always maintained at a constant angle with respect to the first shaft 11 due to the existence of the parallel link 22, regardless of the swing angle of the first arm 13, Accordingly, the swing angle of the second arm 15 with respect to the first axis 11 is uniquely determined.

Also, is there a built-in turning drive mechanism in the second arm 15 that causes the wrist portion 38 having the grinder G provided at the tip thereof to make a turning movement a+ around the axis of the second arm 15? Not particularly shown. Second arm 15
At the end portion on the opposite side from the wrist portion 38 of
Counterweight 3, which is a type of city balance device
9 is fixed, and the gravity of this counterweight 39 achieves the terrifying balance between the axis of the first arm 13.

In the case of the horizontal arm mechanism configured in this way, since the first arm 13 and the second arm 15 are attached to the first shaft 11 in a cantilevered manner, it is necessary to provide a balance device for their weight. A large torsional torque is applied to the first shaft 11, and this torsional torque varies depending on the inclination due to the swinging of the first arm 13 in the vertical plane and in the horizontal plane, so a special gravity balance device is required for this purpose. need to be adopted. A gravity balance device for fulfilling such functions will be explained next. That is, in Figure 2, 40
is a drum 42 around which a wire 41 is wound, and this drum 4.
A rotational force applying mechanism (not shown) consisting of a helical spring or the like (not shown) that applies a rotational force in the direction of winding the wire 41 around the wire 41, and a tension applying device that is attached to the base 29. The wire 41 wound around the drum 42 passes through the circumference of a rotating sheave 44 rotatably attached to the tip of a rotating shaft 43 rotatably mounted on the base 29. , the direction is changed by the rotating sheave 44, and the end is wound 180 degrees around a sheave 47 rotatably attached to the tip of a rod 46 attached to a spherical joint 45 attached to the midpoint of the first arm 13. It is fixed to a fixed point 48 at the end of the cylinder 43.

Therefore, the rotational force acting on the drum 42 is transmitted to the wire 41 and pulls the parallel portion 41'' of the wire in the direction of the rotary sorb 44, so that this tension causes the sheave 47, the rod 4
6. The first arm 13 is pulled vertically through the spherical joint 5, and the first arm 13, the second arm 15, the counterweight 39, etc. of the vehicle act on the spherical joint 45. The rotational moment about the first axis 11 due to the rotational force is canceled out.

In the case of this mechanism, the 17th arm 13 swings downward in a vertical plane about the first leg 11.

When the wire 41 rotates or oscillates around the support shaft 12, the parallel portion 41'' of the wire 41 also rotates around the rotating sheave 44.
The rotating shaft 43, to which a rotating sheave 44 is attached as will be described later in the case of the present invention, is connected to a wire 41'.
Since the structure is such that the rotating sheave 44 rotates along with the rocking movement around the rotating sheave 44, the rotating sheave 44 is tightly rotated in the direction along the wire, so that the wire does not come off the rotating sheave 44. There are no inconveniences.

Here, the principle of the gravity balance device using the wire 41 will be explained with reference to FIG. Now, it is assumed that the spherical joint 45 is attached to the combined center of gravity of the first arm and the second arm, and for the sake of simplicity, the point where the spherical joint 45 is located is indicated by D as shown in FIG. , rotating sheave 4
The position where 5 exists is E, and the first axis 11 and the first arm 13
Let F be the intersection point 23 of each axis with The angle with the horizontal line is θ, the angle DEF is α, the tensile force of the wire acting on point D is P, the elastic modulus of the coiled spring etc. that pulls the wire is the first arm and the second arm acting on point D.
When the combined gravity of the arm is W, the gravitational moment Mw around the first axis 11 is expressed as Mw=W-Rcosθ-W-#sinα-(1), which is exerted by the pulling force of the wire 41. The rotational moment Mp is expressed as Mp=Ph=P-asin tx-(2). Here, when MW=Mp, both moments are balanced, and only twisting occurs in the first axis. In such a state, WAsin α=Pasin α−(3) holds true. Therefore, rearranging this equation, P-(a/W)
・p (4) is obtained, which defines the condition that the tension P of the wire is pulled up by a spring member having a spring constant of a/W=, and the elongation at that time is β. If a coiled spring or the like that satisfies these conditions is used, the weight of the arm will be perfectly balanced. (4)
Since the horizontal and vertical angles α and θ of the first arm are irrelevant to the equation, as long as this condition is satisfied, perfect balance is always established regardless of the swing angle of the first arm. - In order not to satisfy the condition defined by the above equation (4), the spring member built in the tension applying device 40 must be
It has a spring constant of a, and is set so that when the drum 42 is rotated and pulled out by the length of ρ from the free tension state of the spring, the winding state as shown in Fig. 2 is obtained. If there is a possible structure, a complete no\
Lance is what is achieved.

Reference numerals 50, 51, and 52 shown in FIG.
The angle detector detects the swing angle of the arm 13, and the angle detector detects the swing angle of the second arm 15 with respect to the first arm 13, and a row encoder, resolver, potentiometer, or the like is employed.

Next, a device for correcting the direction of the rotating sheave 44 according to the swinging movement of the wire will be explained with reference to FIGS. 4 to 6.

First, the relationship between the above-mentioned rotating sheave and the wire will be briefly explained with reference to FIG.

Consider a case where the younger brother 1 arm 13 swings around the support shaft 12 in a horizontal plane. Consider a case where, when the first arm 13 is in the illustrated position, the rotating sheave 44 on the rotating shaft 43 side and the sheave 47 on the first shaft 13 side are on the same plane as shown in the figure. In this state, the sheave surface of the rotating sheave 44 and the surface formed by the wire 41'' match, so the wire 41'' does not come off from the rotating sheave 44.

However, from this state, when the first arm 13 swings around the support shaft 12 in the direction shown by the arrow X, and the center of the sheave 47 moves in an arc from the position S to the position So, “The wire surface created by the rotating sheave 44
It moves along the conical surface formed by the arcs s, s'', and s'.

Therefore, for example, the first arm 13 rotates 90 degrees and the sheave 4
When the wire 7 reaches the position So, the plane GSHI formed by the wire surface at that position and the sheave surface of the rotary sheave 44 no longer coincides, and the angle between them becomes β. Therefore, if the rotating shaft 43 to which the rotating sheave 44 is attached is rotated by an angle β while the sheave 47 moves from the S position to the So position, the sheave surface of the rotating sheave 44 is always the wire surface formed by the wire 41'. This can prevent the wire from coming off the sheave.

The present invention has been made in view of the above points, and in short, the present invention detects the deviation between the sheave surface and the wire surface in order to make the surface formed by the wire 41' and the sheave surface of the rotating sheave 44 closely match. By controlling the rotation of the rotating shaft 43 in a direction that eliminates this deviation, both surfaces are always brought into alignment, thereby preventing the wire from coming off.

A specific embodiment for realizing this is shown in FIGS. 4 and 5.

In these figures, a rotary shaft 43 rotatably supported by a bearing 53 provided on the base 2 has a fixed support shaft 54 perpendicular to the axis at its tip. and
A rotary sheave 44 is rotatably attached to the support shaft 54 via a bearing 55. Further, a fixing plate 488 is fixed to the tip of the rotating shaft 43, which does not form the fixing point 48, and one wire per day is wound around and fixed to this fixing plate 48a. Wire 41. is reversed by the rotating sheave 47 shown in FIG. It wraps around the rotating sheave 44 by approximately 90 degrees, and further wraps around the rotating shaft 43.
It is wound around the tram 42 of the tensioning device attached to the rotating shaft 43 shown in FIG. Out of the way
The above wire 41. l and 411. constitutes the ``parallel portion 41 of the wire'' shown in FIG.

As shown in detail in FIG. 5, the end of the support shaft 54 is provided with a detector mounting base 57 which is rotatable around the support shaft 54 via a bearing 56. A lever 59 is attached to the pin 58 which is once attached to the lever 57 and is swingable around the pin 58.
The tip of the lever 59 supports the wires 41a and 41 with the parallel portion 41'' of the wire.A bracket 60 parallel to the support shaft 54 is fixed to the intermediate portion of the lever 59, and a Dogs 61 and 62 facing each other are fixed respectively, and -Fj of the detector mounting base 57 is inserted between the dogs 61 and 62, and a detection piece 64 facing the dog 62 is inserted into this insertion portion. A limit switch 65 having a detection piece 63 facing the dog 61 is attached to the limit switch 66 and the limit switch 65 having a detection piece 63 facing the dog 61.The relationship between these dogs and the detection piece of the limit switch is as shown in FIG. When the dog 61 is brought into contact with the detection piece 63 by swinging clockwise around When the dog 61 is rotated to
2 is in contact with the detection piece 64, and there is a slight dead zone region where both limit switches 65 and 66 are not activated.

Further, at the end of the rotating shaft 43 opposite to the rotating sheave 44,
The sprocket 67 is fixed, and the sprocket 70 attached to the output shaft 69 of the motor 68 with a reduction gear is
It is connected to the sprocket 67 by a chain 71.

Next, the operation of the embodiment F will be explained. Rotating shaft 43
When the first arm 13 shown in FIG. 2 swings while the wire 41a is stopped and the wire 41a swings relative to the support shaft 54, the lever 59 whose tip is fixed to the wire 41a moves to the pin 58.
oscillates around the center. Lever 59 as shown in Figure 5
When the is rotated clockwise, the dog 61 comes into contact with the detection piece 63, the limit switch 65 is turned on, and this signal causes the motor 68 to rotate and the sprockets 67 and 70 to rotate.
Then, the rotating shaft 43 is rotated via the chain 71, and the lever 59 is rotated counterclockwise relative to the pin 58. This movement causes the dog 6 attached to the lever 59 to
1 separates from the detection piece 63, and the limit switch 65 turns OFF.
F (at this time, the limit switch 66 is also OFF), the motor 68 stops rotating, and the rotation shaft 4
Stop 3.

Conversely, when the wire 41a swings counterclockwise and the arm 59 swings counterclockwise around the pin 58, the dog 62 pushes the detection piece 64, and the limit/noto isochi 66 turns O.
N, the motor 68 is driven to rotate in the opposite direction, and the rotating shaft 43 is rotated so that the lever 59 rotates clockwise relative to the pin 58.

The limit switches are set so that when the wire 41a is pulled in a direction perpendicular to the support shaft 54, the limit switches 65 and 66 operated by the dogs 61 and 62 are both in the OFF state (the dead zone region). By determining the relative positional relationship between the motor 64 and each tosog, the direction of the rotating sheave 44 can be corrected so that the wire 4-1a is always perpendicular to the support shaft 54 by the operation of the motor 64 described above. I can do it.

Further, when the first arm 13 swings in the horizontal force direction about the support shaft 12, the wire 41a swings about the support shaft 54, but the lever 5 attached to the wire 41a
9 is attached to a detector mounting base 57 that is rotatable around the support shaft 54, so that the lever 59 can rotate following the swinging of the wire 41a, and the lever 59 can be rotated in accordance with the swinging of the wire 41a. The direction of the wire 41a is detected very accurately even when it is oriented.

In the above embodiment, the present invention is applied as a device for adjusting the direction of the gravity balance wire and the sheave surface of a horizontal multi-joint arm mechanism as shown in FIG. The present invention is not limited to the example, but can be applied to any mechanism in which a wire wound around the sheave surface is shaken and detached from the rotating sheave.

As described above, the present invention includes a first shaft rotatably attached to the base, a first arm swingably attached to the end of the first shaft, and an imager mounted on the base. balance the gravity applied to the first arm, which comprises a rotating sheave, which is connected to the rotating sheave, and a wire whose one end is connected to the first arm and whose other end is connected to the tension sheave at every position through the circumference of the rotating sheave. The device includes a position detector that detects the position of the wire that swings around the rotating sheave in response to the swinging of the first arm, and a position detector that detects the position of the wire that swings around the rotating sheave in response to the swinging of the first arm, and a position detector that detects the position of the wire that swings around the rotating sheave in response to the swinging of the first arm. Sheave drive that rotates in the direction of wire swing.
An automatic for a sheaf car characterized by having a 1 and 1 device? i! Since it is a regular device, the direction of the sheave is automatically adjusted so that the direction of the sheave matches the wound wire, and the wire is automatically prevented from falling off the sheave surface.

[Brief explanation of the drawing]

Figure 1 is a side view showing an example of a conventional articulated robot.
Fig. 2 is a perspective view of the entire horizontal multi-joint arm mechanism to which the present invention can be applied, and Fig. 3 is the operation of a balance device to eliminate the rotational moment about the first axis of the entire arm mechanism shown in Fig. 2. A schematic configuration diagram illustrating the principle, FIG. 4 is a front view including a partial cross section of the entire automatic correction device in the sheave direction according to an embodiment of the present invention, and FIG. 5 is an enlarged view of the section viewed from arrow A in FIG. FIG. 6 is a schematic diagram showing the relationship between the rotating sheave and the wire. (Explanation of symbols) 13...First arm, 29...Base 44...
Rotating sheave, 41a...Wire 40...Tension device 65.66...Limit switch ((jχ detector) 6
8...Motor (sheave drive device). Applicant Kobe Steel, Ltd.

Claims (1)

[Claims] 1. A first shaft rotatably attached to the base, a first arm swingably attached to the end of the first shaft, a rotating sheave attached to the base, and one end attached to the first arm. and a wire whose other end is connected to a tensioning device through the circumference of a rotating sheave. a position detector that detects the position of the wire that swings around the rotating sheave in response to the movement of the wire; and a sheave drive device that rotates the rotating sheave in one direction in which the wire swings in response to a signal from the position detector. An automatic correction device for sheave direction, comprising: