GB2171222A

GB2171222A - Robot spraying system

Info

Publication number: GB2171222A
Application number: GB08504024A
Authority: GB
Inventors: Tomoo Shokawa; Takatoshi Ueno; Minoru Nonaka; Tetsuji Yoshida; Shinobu Yamazaki; Shigemasa Suematsu; Kiyoshi Hasegawa; Shiro Kamiko; Susumu Aoki
Original assignee: Shimizu Construction Co Ltd; Kobe Steel Ltd; Nihon Cement Co Ltd; Nichias Corp
Current assignee: Shimizu Construction Co Ltd; Kobe Steel Ltd; Nihon Cement Co Ltd; Nichias Corp
Priority date: 1985-02-16
Filing date: 1985-02-16
Publication date: 1986-08-20
Also published as: GB8504024D0

Abstract

A system for spraying a coating material onto an elongated construction workpiece includes an industrial robot 10 and a spray nozzle 106 movably mounted thereon. The robot includes drive means to move it along a path of travel on a floor, a device for detecting spray nozzle movement, a device for detecting the distance of travel of the robot, and drive means for driving the spray nozzle; a device for feeding the coating material to the spray nozzle; a valve for controlling the flow of the coating material through the nozzle; drive means for opening the flow control valve, a device for detecting the opening of the flow control valve, and a device for detecting the position of the robot with respect to the elongated construction workpiece. A computer 12 is programmed to be responsive to signals from the detecting devices for preparing a program relating to the sequential movements of the robot and spray nozzle, the opening of the flow control valve and the position of the robot. The computer controls the drive means in accordance with the program to effect a replay of the spraying operation. <IMAGE>

Description

SPECIFICATION Robot system for spraying coating material onto workpiece Background of the invention Filed of the invention This invention relates to a system for controlling the operation of an industrial robot movable along a programmed path on a floor and particularly to such a robot for spraying a coating material onto a workpiece.

Prior art In the construction of a multi-storied building, a refractory material is sprayed onto steel structural members such as beams in the building. This spraying includes a wet spraying, a dry spraying and a semi-wet spraying. In the case where the spraying operation is carried out manually using a spray gun or the like, the operator tends to inhale the sprayed refractory material. This is quite undesirable from a viewpoint of the operator safety, and this problem is serious particularly when the refractory material to be sprayed contains rock wool made of fine fibrous material. The fibrous material causes irritation to the throat and skin of the operator. To avoid this, the operator must wear a spray mask and a bulky clothing or the like so as not to expose his skin to the sprayed material.

Therefore, the spraying operation has not heretofore been carried out efficiently. In addition, the spraying operation must be repeated on each floor of the multi-storied building and therefore requires much labor. In order to overcome the above difficulties, there has recently been proposed an industrial robot which is movable along a predetermined path for spraying a coating material onto a workpiece under the control of computer means. Such a robot is disclosed in Japanese Patent Application Kokai Nos. 59-226909 and 59-227373. However, there has heretofore not been proposed means for efficiently controlling the feeding of the coating material from a spray nozzle of the robot.

Summary of the invention It is therefore an object of this invention to provide an industrial robot system for performing a spraying operation or the like efficiently.

According to the present invention, there is provided a robot system for automatically spraying a coating material onto an elongated workpiece which comprises: (a) an industrial robot comprising (i) a body, (ii) a spray nozzle movably mounted on the body, the spray nozzle being connected to a source of supply of the coating material for spraying the coating material onto the workpiece, (iii) first drive means for driving the robot to move along a path of travel on a floor, (iv) means for detecting the movement of the spray nozzle to feed a first detection signal, (v) means for detecting the distance of travel of the robot to feed a second detection signal, and (vi) second drive means for driving the spray nozzle; and (b) computer means including a memory and being programmed to be responsive to the first and second detection signals for preparing a program of the sequential movements of the robot and spray nozzle and storing it in said memory, the computer means controlling the first and second drive means in accordance with the program to effect a replay of the spraying operation.

Brief description of the drawing Figure 1 is a schematic view of a spray robot system provided in accordance with the present invention; Figure 2 is a block diagram of the spray robot system; Figure 3 is a block diagram of a spray robot used in the spray robot system; Figure 4 is a plan view of a base of the spray robot, showing a truck; Figure 5 is a side-elevational view of the base of the spray robot; and Figure 6 is a cross-sectional view of a position sensor for a spray nozzle of the spray robot.

Description of the preferred embodiment of the invention Figure 1 shows a spray robot system embodying the present invention. Figure 2 shows a block diagram of the spray robot system. This system comprises a spray robot 10 and a control unit 12 for controlling the operation of the robot 10, the control unit comprising a computer 14 and an I/O interface 16. Figure 3 shows a block diagram of the spray robot 10. The robot 10 comprises a base 18 and a body 20 mounted on the base 18, and the base 18 includes a rectangular base plate 22 and four vertical outriggers 24a to 24d mounted on the four corners of the base plate 22, respectively, each of the outriggers being extensible along its axis as later described.As shown in Figures 4 and 5, a hydraulic motor 26 is mounted on the base plate 22, and a transverse shaft 28 is connected to the hydraulic motor 26 via a gear box 30 for being driven for rotation about its axis, the shaft 28 being borne in bearings (not shown) on the base plate 22. A pair of longitudinal shafts 32a and 32b are connected respectively to the opposite ends of the transverse shaft 28 via gear boxes 34 and 36 on the base plate 22 for being driven for rotation about their respective axes, the shafts 32a and 32b being journalled in bearings (not shown) mounted on the base plate 22. As best shown in Figure 5, each of the outriggers 24a to 24b comprises a cylindrical body 40a and a piston 40b received in the cylindrical body 40a for sliding movement therealong, the piston 40b having a rack portion (not shown).The pistons 40b of the outriggers 24a and 24b are connected at their rack portions respectively to the opposite ends of the longitudinal shaft 32a via gear boxes 42 and 44 for vertical movement along their respective cylindrical bodies 40a.

Similarly, the pistons 40b of the outriggers 24c and 24d are connected at their rack portions respec tively to the opposite ends of the longitudinal shaft 32b via gear boxes 46 and 48 for vertical movement along their respective cylindrical bodies 40a.

Thus, the hydraulic motor 26 drives the outriggers 24a to 24d to extend or retract along their axes. A potentiometer 50 is associated with one of the pistons 40b of the outriggers 24a to 24d for detecting the amount of vertical movement thereof Mounted below the base plate 22 is a truck 52 which comprises a body 52a in the form of a rectangular plate, a pair of front wheels 54a and 54b, and a pair of rear wheels 56a and 56b. A vertical shaft 58 is fixedly secured to the body 52a at its center and is rotatably connected to the base plate 22 via a bearing (not shown) in a manner not to permit vertical movement of the shaft 58 relative to the base plate 22. A gear 60 is mounted on the vertical shaft 58. A hydraulic motor 62 is mounted on the lower surface of the base plate 22 and is connected to a gear box 64 on the base plate 22.

An output gear 66 of the gear box 64 is in mesh with the gear 60. Thus, the hydraulic motor 62 drives the truck body 52a for angular movement about the vertical shaft 58 relative to the base plate 22. An encoder 68 is operatively associated with the vertical shaft 58 for detecting the amount of angular movement of the truck body 52a.

A pair of sprockets 70a and 70b are mounted respectively on axles 71a and 71b of the rear wheels 56a and 56b and are spaced transversely of the rectangular truck body 52a. Two hydraulic motors 72a and 72b are mounted on the lower surface of the body 52a and are connected to two gear boxes 74a and 74b, respectively. Two sprockets 76a and 76b are connected to output shafts of the gear boxes 74a and 74b, respectively. A chain 78a extends around the sprockets 70a and 76a while a chain 78b extends around the sprockets 70b and 76b. Thus, the hydraulic motors 72a and 72b drive the respective rear wheels 56a and 56b to move the spray robot 10 along the floor.

A bracket 80 is mounted on the lower surface of the body 52a, and a lever 82 is pivotally connected to the bracket 80 at one end thereof. A travel distance-detecting wheel 84 having a toothed peripheral edge is rotatably mounted on the free end of the lever 82. An axle 86 is fixedly secured to the wheel 84, and an encoder 88 is secured to the axle 86 for detecting the amount of rotation of the axle 86 to determine the travel distance of the truck 52.

A spring 90 extends between the lower surface of the truck body 52 and the lever 82 for holding the travel distance-detecting wheel 84 into rolling engagement with the floor during the travel of the spray robot 10. The hydraulic motors 26, 62, 72a and 72b, the potentiometer 50 and the encoders 52, 68 and 88 are electrically connected to the computer 14 via the l/O interface 16. These hydraulic motors are operated through a control panel 94.

An articulated arm 98 is mounted on the robot body 20 and is capable of extension, contraction and rotation. Drive means 100 comprising electric motors drive the arm 98 to effect these movements, and detection means 102 is provided on the robot body 20 for detecting these movements of the arm 98. A nozzle holder 104 is connected to the distal end of the articulated arm 98 and is capable of angular movement about its proximal end in every direction, the nozzle holder 104 holding a spray nozzle 106. Drive means 112 comprising electric motors drive the spray nozzle 106 to effect these angular movements, and detection means 114 is provided on the robot body 20 for detecting these angular movements. The drive means 100 and 112 and the detection means 102 and 114 are connected to the computer 14 via the l/O interface 16.

Two flexible hoses 108 and 110 are connected at their one ends to the spray nozzle 106. The other end of the hose 108 is connected to a rock wool feed device 116. The rock wool feed device 116 comprises a roots blower 118 and a rock wool feeder 120 connected to the roots blower 118 via a hose 108a. The rock wool feeder 120 comprises a body 122 in the form of a box, a chute 124 received in the upper portion of the body 122 for receiving rock wool, an inner box 122a received in the lower portion of the box 122 and communicates with the chute 124. The hoses 108 and 108a are connected to the inner box 122a at opposite sides thereof. An agitating blade member 128 and a pair of agitating blades 130 are mounted within the chute 124. A vibrator 132 is attached to the outer surface of the chute 124 for imparting vibration thereto.

The other end of the hose 110 is connected to a cement slurry feed device 134 which comprises a pair of mixers 136 and a slurry feed pump 138.

Each of the mixers 136 comprises a box 139 and an agitator 140 associated with the box 139. Cement 142 is supplied to each of the boxes 139 together with water 143 to form a cement slurry with the aid of the agitator 140. One end of the hose 110a is received in one of the boxes 139 while the other end is connected to an inlet side of the slurry feed pump 138 to feed the cement slurry thereto.

The outlet side of the feed pump 138 is connected to the spray nozzle 106 via the hose 110.

Rock wool 126 is supplied to the chute 124 and a constant amount of the rock wool is fed from the rock wool feeder 120 to the spray nozzle 106 via the hose 108, and a constant amount of the cement slurry is fed from the feed pump 138 to the spray nozzle 106 via the hose 110, so that the rock wool and the cement slurry are mixed together in the spray nozzle 106. This mixture constituting a refractory material is discharged from the spray nozzle 106.

A position sensor 148 is mounted on the nozzle holder 104. The position sensor 148 will now be described with reference to Figure 6 An casing 150 is fixedly secured to the nozzle holder 104 through a mounting plate 152. A pair of brackets 154 and 156 are mounted on the mounting plate 152 and are disposed adjacent to the opposite end walls of the casing 150, respectively. A probe rod 158 is slidably passed through the brackets 154 and 156.

An actuator member 160 is fixedly mounted on the probe rod 158, the actuator member 160 having a hole 162. A potentiometer 164 is fixedly mounted within the casing 150 and includes an elongated body 164a and a resistor (not shown) received in the body 164a therealong. A pin 166 is mounted on the potentiometer body 164a for movement therealong and has at its inner end an electrical contact (not shown) disposed in sliding contact with the resistor. A rounded free end of the pin 166 is received in the hole 162 of the actuator member 160.

A coil spring 168 is wound around the probe rod 158 and acts between the bracket 156 and the actuator member 160 for normally urging the probe rod 158 into its extended position. An expansible cover member 170 is secured at one end to the end wall of the casing 150 via an end plate 172 through which the probe rod 158 extends, the cover member 68 being fitted on that portion of the probe rod 158 extending from the end plate 172. The potentiometer 164 is electrically connected to the computer 14 via the l/O interface 16.

As shown in Figure 5, a photosensor 176 is mounted on the front of the base 18 for detecting an obstacle on the path of travel of the spray robot 10 to feed a detection signal to which the computer 14 is responsive via the I/O interface 16 to deactivate the hydraulic motors 72a and 72b to stop the running spray robot 10. Also, a pair of pressure-sensitive tape switches 178 are attached to each side of the base 18. Each of the pressuresensitive switches 178, which subjected to external pressure, feeds a detection signal to which the computer 14 is responsive via the I/O interface 16 to deactivate the hydraulic motors 72a and 72b to stop the running spray robot 10.

The operation of the spray robot system will now be described.

For spraying the refractory material composed of rock wool and cement slurry onto beams on each floor of a multi-storied building, the spray robot 10 is first taught the spraying operation on a selected one of the floors of the building. Then, this spraying operation is replayed on the other floors under the control of the control unit 12. More specifically, the rock wool feed device 116 and the cement slurry feed device 134 are placed on the first floor of the building. The spray robot 10 is conveyed to the selected floor using a lift or the like. First, a path of travel of the spray robot 10 is marked on the surface of the selected floor. Then, targets are marked on the beam at locations or stations spaced along the travel path, each of the targets being composed of three dots. Then, the spray robot 10 is positioned at a stating point of the travel path.Then, the operator operates the hydraulic motors 72a and 72b to drive the rear wheels 56a and 56b to move the spray robot 10 along the travel path and then deactivates these motors to cause the spray robot 10 to stop at the first station.

Then, the hydraulic motor 26 is operated to extend the piston 40b of the outriggers 24a to 24d to move the truck 52 and the robot body 20 upwardly so that the front and rear wheels 54a, 54b, 56a and 56b and the distance-detecting wheel 84 are held away from the floor. The distance between the starting point and the first station is detected through the distance-detecting wheel 84 and the encoder 88 and is stored in the memory of the computer 14. The amount of extension of the outriggers 24a to 24d are detected by the potentiometer 50 and stored in the memory of the computer 14.

Then, the operator holds the spray nozzle 106 and brings it into contact with the three targets dots until the probe rod 158 is retracted 100 mm, thereby determining a reference amount of retraction of the probe rod 158. These sequential movement of the spray nozzle 106 is stored in the memory of the computer 14. This retraction of the probe rod 158 is detected by the potentiometer 164 as described above.

Then, the operator opens a flow control valve 184 connected to the spray nozzle 106 and brings the spray nozzle 106 around to spray the refractory material, fed from the rock wool feed device 116 and the cement slurry feed device 134, onto the beam. This movement of the spray nozzle 106 is stored in the memory of the computer 14. Detection means 190 is provided for detecting the opening and closing the valve 184 to feed a detection signal. Drive means 186 for opening and closing the valve 184 is provided on the spray robot 10 which drive means is operated in response to the detection signal from the detection means 190 under the control of the computer 14 at a replay of the spraying operation on another floor. In this way, the operator teaches the spray robot 10 the spraying operation.

Upon completion of the spraying operation at the first station, the outriggers 24a to 24d are contracted to bring the front and rear wheels 54a, 54b, 56a and 56b and the distance-detecting wheel 84 into rolling engagement with the floor. Then, the spray robot 10 is operated to move from the first station to the next or second station and to perform the spraying operation in the manner described above. This procedure is repeated at the subsequent stations. When it is necessary to change the direction of travel of the spray robot 10, the outriggers 24a to 24d are extended to move the front and rear wheels 54a, 54b, 56a and 56b and the distance-detecting wheel 84 away from the floor. Then, the hydraulic motor 62 is operated to angularly move the truck 52 about the shaft 58 through a required angle via the gear box 64 and the gears 66 and 60.This angular movement is detected by the encoder 68 and stored in the memory of the computer 14.

The sequential movements of the spray robot 10 and the spray nozzle 106 are stored in the memory of the computer 14 through the first to final stations to provide a program for a replay of the spraying operation.

For replaying the spraying operation on another floor, the spray robot is transferred to that floor and is positioned at a starting point of a travel path corresponding to the travel path on the aforesaid selected floor. Then, under the control of the computer 14, the spray robot 10 is operated in accordance with the replay program to effect a replay of the spraying operation.

There are occasions when the floor on which the replay of the spraying operation is to be effected is not fully flat and is rugged at some of the stations where the spray robot 10 is to stop. In this case, at the time of the replay, the probe rod 158 is brought into contact with those spots of the beam which are offset from those determined by the target dots. Therefore, the amount of retraction of the probe rod 158 is different from the reference amount of retraction described above. The potentiometer 164 delivers a signal representative of this retraction amount in response to which the computer 14 calculates a difference between the accurate position of the spray robot 10 and the position of the robot 10 at each station on this floor and feeds output information representative of this difference. The drive means 112 is operable in response to this output information to move the spray nozzle 106 into the proper position at each station.

Claims

1. A robot system for spraying a coating material onto an elongated workpiece which comprises: (a) an industrial robot comprising (i) a body, (ii) a spray nozzle movably mounted on said body, (iii) first drive means for driving said robot to move along a path of travel on a floor, (iv) means for detecting the movement of said spray nozzle to feed a first detection signal, (v) means for detecting the distance of travel of said robot to feed a second detection signal, and (vi) second drive means for driving said spray nozzle to move around; (vii) means for feeding the coating material to said spray nozzle; (viii) a flow control valve for controlling the flow of the coating material through said spray nozzle; (ix) third drive means for opening said flow control valve, (x) detection means for detecting the opening of said flow control valve to feed a third detection signal, and (xi) means for detecting the position of said robot with respect to said elongated construction workpiece to feed a fourth detection signal; and (b) computer means including a memory and being programmed to be responsive to said first, second, third and fourth detection signals for preparing a program relating to the sequential movements of said robot and spray nozzle, the opening of said flow control valve and the position of said robot and storing it in said memory, said computer means controlling said first, second and third drive means in accordance with said program to effect a replay of the spraying operation.

2. A robot system according to claim 1, in which said robot is caused to stop at predetermined stations spaced along the travel path, said means for detecting the position detecting the position of said robot at each station to feed said fourth detection signal, said computer means being programmed to be responsive to said fourth detection signal for storing in said memory data representative of the accurate position of said robot, said computer means being responsive to the fourth detection signal at the time of the replay of the spraying operation to calculate a difference between said accurate position and the position of said robot at each station at the time of the replay of the spraying operation to feed output information representative of said difference, and said second drive means being operable in response to said output information to move said spray nozzle into its proper position.

3. A robot system according to claim 2, in which said position sensor comprises a casing fixed to said spray nozzle, a probe rod mounted on said casing for movement along its axis between an extended position and a retracted position and having one end extending through said casing, a spring acting on said probe rod for normally urging it into its extended position, and a potentiometer operatively connected to said probe rod for detecting the amount of retraction of said probe rod.

4. A robot system according to claim 1, in which said robot comprises a plurality of verticallydisposed elongated outriggers extensible along its axis to move said robot body away from the floor, and fourth drive means for extending said outriggers into their extended positions, and means for detecting the amount of extension of said outriggers to feed a fifth detection signal, said computer means being responsive to said fifth detection signal to store in said memory data representative of the amount of extension of said outriggers, and said computer means controlling said fourth drive means in accordance with said data at the time of the replay of the spraying operation.

5. A robot system according to claim 4, in which said robot comprises a truck mounted on a lower surface of said robot body for angular movement about a vertical axis and having wheels in rolling engagement with the floor, fifth drive means for angularly moving said truck about said vertical axis through a desired angle, and means for detecting the angular movement of said truck to feed a sixth detection signal, said computer means being responsive to said sixth detection signal to store in said memory data representative of said angular movement, and said computer means controlling said fifth drive means in accordance with said data.