Industrial robot

An industrial robot for casting products by pouring molten metal in a ladle mounted on an arm thereof to successively conveyed molds, comprises a drive mechanism for driving the ladle to incline with respect to the mold, means for measuring a level of molten metal in the mold, means for detecting an inclination rate of the ladle and a central processing unit having a memory for storing an optimum level of molten metal in the mold and inclination rate of the ladle, the central processing unit being adapted to receive a level data from the measuring means and an inclination rate data from the detecting means, compare the data with the optimum level and inclination rate, calculate deviations of the data from the optimum level and inclination, and supply control signals to the drive mechaniam to control the latter optimally.

BACKGROUND OF THE INVENTION 
The present invention relates to an industrial robot, and, particularly, to 
an industrial robot for use in a casting field to pour molten metal into a 
mold. 
In the casting industry, a pouring of molten metal into a mold has been 
performed mainly by skilled personnel since it is very important to select 
a pouring rate suitably, otherwise, molded products may be deformed, or 
the mold may be broken. However, environmental working conditions of the 
casting factory are severe due to high temperature and dusty air which are 
not suitable for human workers. In order to solve this problem, a 
substitution of a robot for skilled personnel has been considered and an 
example of this consideration is disclosed in Japanese Patent Application 
Laid-open No. 229463/1986. An industrial robot disclosed in the latter is 
characterized by reducing an effect of high temperature environment on a 
driving mechanism of the robot. 
In such a conventional industrial robot, a transfer of techniques of 
skilled personnel based on experiences and feelings to the robot has not 
been realized to the extent that the robot can perform the techniques 
reliably. 
SUMMARY OF THE INVENTION 
An object of the present invention is into provide an industrial robot by 
which a pouring of molten metal to a mold is performed under conditions 
which are optimum for the mold so as to prevent a breakage of the mold and 
deformation of molded products. 
The above object of the present invention is achieved by a provision of an 
industrial robot having a ladle mounted on an arm of the robot in which 
the ladle is inclined in a vertical plane by a driving mechanism of the 
robot to pour molten metal therein into a mold while measuring a level of 
molten metal in the mold by means of a measuring device. The level data of 
molten metal in the mold and an inclination rate of the ladle are sent to 
a CPU in which these data are compared with respective optimum values 
preliminarily stored in a memory of the CPU to obtain deviations of the 
respective data upon which control signals are sent to the driving 
mechanism to control pouring rate an optimum. 
According to the present device, the pouring rate of molten metal from the 
ladle into the mold is controlled to be optimum, so that the problems of 
breakage of the mold and deformations of products are prevented.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
In FIG. 1, which illustrates an embodiment of the present invention, a 
robot is arranged on one side of a conveyer 2 for transporting a mold 1 in 
a direction perpendicular to the drawing sheet so that molten metal is 
poured thereby into the mold 1. The robot includes a main body 4 and an 
arm 5 extending therefrom above the conveyer 2. The arm 5 is composed of a 
first arm portion 5A having one end rotatably connected to an upper 
portion of the main body 4 and a second arm portion 5B having one end 
articulated with the other end of the first arm portion 5A. A gear 7 is 
provided around the articulation for driving a ladle 6 supported by a link 
mechanism 8 composed of the other end of the second arm portion 5B and an 
arched rack 8A meshed with the gear 7 to incline the ladle 6 above the 
mold 1 thereby to pour molten metal in the ladle 6 into the mold 1. The 
robot is preliminarily taught that a pouring end 6A of the ladle 6 comes 
to a position just above an opening 1A of the mold 1. 
A ceiling 9 over the conveyer 2 suspends a distance meter 10 for measuring 
a level h of molten metal in the mold 1 so that the level of the molten 
metal being poured is measured continuously by the meter 10 to determine 
an increaseing rate of the level h. The increasing rate of the level h is 
related to the pouring rate of the molten metal, and, hence, the 
inclination rate of the ladle 6. 
An optimum value of the inclination rate of the ladle 6 depends upon the 
mold 1 to be used and the physical properties of a mold product to be 
produced, which has been determined empirically by those skilled 
personnel. The optimum value concerning the inclination rate of the ladle 
6 is preliminarily stored in a memory of a CPU 11 housed in the main body 
4, and is compared with an actual rate. The ladle 6 is controlled on the 
basis of the deviation of the actual value from the stored value. 
FIG. 2 shows a control portion of the present robot. In FIG. 2, the rising 
rate of the level of the molten metal in the mold 1 and the inclination 
rate of the ladle 6 are inputted through an I/O port 12 to the CPU 11 as 
measured values. In the CPU 11, these measured values are compared with 
the optimum values stored in the memory and a control signal based on a 
resultant deviation is supplied through the I/O port 12 to a control 
device 13 of the ladle 6, upon which a drive device 14, i.e., the link 
mechanism 8 including the gear 7 and the rack 8A, is actuated to correct 
the inclination rate of the ladle 6 to the optimum rate thereby to obtain 
an optimum amount of poured molten metal. 
In this case, the position of the robot arm 5 is controlled by the control 
device 15 on the basis of the control signal supplied thereto from the CPU 
11 through the I/O port 12 so that the drive device 16 is operated such 
that the optimum position of the ladle 6 is obtained. 
The above operation of this invention is shown by a flowchart in FIG. 3. In 
FIG. 3, first, a pouring of molten metal from the ladle 6 into the mold 1 
commences and a level and a rising rate of the molten metal level in the 
mold 1 are detected by the meter 10 and inputted to the CPU 11 in which 
they are checked with respect to the stored optimum values in the step 
100. In the step 101, these measured values are examined to determined 
whether or not they are coincident with an ideal pattern indicative of the 
optimum values. If the actual values are coincident with the ideal 
pattern, the pouring operation is continued in the step 102. If they are 
not coincident with the ideal pattern, a deviation of the actual 
inclination rate of the ladle 6 from the optimum value is calculated in 
the step 103 upon which the drive device 14 of the ladle 6, i.e., the gear 
7 is rotated in either direction to regulate it so that the actual 
inclination rate becomes the optimum value in the step 104. Then, the 
operation is returned to the step 101. It should be noted that the 
measurement of the actual inclination of the ladle 6 can be performed 
easily by providing a motor having an encoder for measuring a rotation 
number and a position thereof at the center of the gear 7 and detecting a 
rotation angle of the gear 7 having a specific geometric relation to the 
rack 8A and the link mechanism 8. Further, it should be noted that the CPU 
has data concerning the relation between the position of the gear 7 and 
the inclination of the ladle 6, and data concerning relation between the 
flow-rate of the molten metal with respect to a minute variation of the 
inclination angle of the ladle 6 at respective angles. The inclination 
rate of the ladle 6 can be calculated on the basis of the positional 
variation of the gear 7. 
The level of molten metal in the mold 1 which is continuously measured by 
the measuring device 10 is examined to determine whether or not the level 
reaches a level in the step 105. When the level reaches the predetermined 
level, the inclination of the ladle 6 is checked in the step 106 and the 
ladle 6 is rotated into the reverse direction to stop the pouring of 
molten metal to the mold 1 in the step 107. Then, in the step 108, it is 
determined whether or not the pouring of molten metal to all of the 
conveyed molds 1 is completed and, if so, the operation is finished. 
When the determination in the step 105 is negative, the operation is 
returned to the step 100. 
When the pouring operation into the molds 1 is not completed, it is 
determined in the step 109 whether or not there is enough molten metal in 
the ladle 6 for molding subsequent work. If so, a pouring into a next mold 
1 is started in the step 110, and the same operation described above is 
repeated. If the ladle 6 does not have enough molten metal, the ladle 6 is 
made up with molten metal in the step 111, and the operation is shifted to 
the step 110. 
The measuring device 10 for measuring the level or depth h of molten metal 
in the mold 1 may be a conventional distance meter such as an ultrasonic 
type or a laser type. 
As described hereinbefore, according to the present invention, it is 
possible to remove the necessity of experienced personnel in the casting 
factory.