JPH052455B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a grinder robot device, and more particularly to a grinder robot device suitable for automatically grinding cast burrs, sprue marks, weir marks, and the like.

``Prior Art and its Problems'' In a grinder work robot device, there are various difficulties in teaching the robot the final completion position of the grinder work.

The main reason for this is that, unlike welding work or painting work, in grinder work, the final work line or work surface is inside the workpiece and has not yet become apparent, so it is impossible to teach it directly.

Therefore, in an example of a conventional device, a workpiece of the same type that has already undergone grinding work is prepared separately as a teaching workpiece, and the robot is taught the work completion position using this workpiece. Grinding work is performed on unfinished workpieces based on the obtained data.

However, there is no guarantee against variations in the dimensional accuracy of the workpiece or misalignment of the workpiece.
Another problem is that a teaching workpiece is required, and furthermore, the work load for teaching using the teaching workpiece is large.

In addition, for workpiece setting deviation,
This problem can be solved by using a highly accurate device for setting the workpiece, but this increases the cost and increases the workload.

It has also been proposed that a special sensor be attached to the robot to automatically follow the teaching work to reduce the burden of teaching work, but this requires a special sensor and requires a mechanism to attach it to the robot. There are problems such as having to do this.

OBJECT OF THE INVENTION An object of the present invention is to provide a grinder robot device which solves the above-mentioned problems and greatly facilitates teaching.

``Structure of the Invention'' The grinder working robot device of the present invention includes a robot body, a grinder held at the wrist of the robot body, a reaction force detector that detects a reaction force acting on the grinder, and a control device that controls them. The control device is equipped with a teaching input means that receives a teaching start point and a teaching end point that indicate a rough working area from the operator, and a trajectory that connects the taught teaching start point and teaching end point by a predetermined interpolation method. a calculation means for calculating position control data of the robot body such that the grinder can move along the same line; and a calculation means for calculating position control data of the robot body such that the grinder can move along the same line; preliminary execution means for detecting the position of the surface of the area; actual position data detection means for obtaining position data of an actual starting point and an actual end point indicating the actual working area in correspondence with the teaching starting point and the teaching ending point, respectively, during the preliminary execution; It has a limit calculation means for obtaining a working limit as a trajectory connecting the actual starting point and the actual ending point by a predetermined interpolation method, and a main execution means for executing the subsequent main grinding work so as not to exceed the working limit. This is a structural feature.

"Example" The present invention will be described in more detail below based on the example shown in the drawings. Here, FIG. 1 is a front view of a grinder working robot device according to an embodiment of the present invention, and FIG.
The figure is the same side view, and Figure 3 is a schematic diagram of a workpiece for explaining the weir trace grinding work by the device shown in Figure 1.
FIG. 4 is a characteristic diagram showing the relationship between reaction force and time before and after the start of operation. Note that the present invention is not limited thereby.

The grinder robot device 1 shown in FIGS. 1 and 2 includes an orthogonal coordinate robot 2 having three movement axes: an X-axis, a Y-axis, and a Z-axis, and a wrist portion 2a of the orthogonal coordinate robot 2. It basically consists of a grinder 3, a reaction force detector 4 built into the grinder 3, and a control device 5 including a computer for controlling these.

The orthogonal coordinate robot 2 has the same configuration as the conventionally known structure, and as described above, the arm portion has X, Y, and Z coordinates.
The wrist part 2a has degrees of freedom in three axes of α, β, and γ.
It has three degrees of freedom of rotation. The position or angle of the arm portion or wrist portion 2a can be detected with high precision using a built-in sensor such as a resolver or encoder.

The grinder 2 has a conventionally known configuration, and performs grinding work by rotating a grindstone 3a.

The reaction force detector 4 has a conventionally known configuration, and specifically includes, for example, a load cell or a load current detector for a grinder.

The control device 5 is similar in appearance to a conventional control device, but differs in its function. That is, the control device 5 has a teaching input function in which a teaching start point and a teaching end point indicating an approximate work area are taught by the operator, and a trajectory connecting the teaching starting point and teaching end point using a predetermined interpolation method. a calculation function that calculates position control data for controlling the position of each degree of freedom of the robot 2 so that the tip of the grinding wheel 3a of the grinder 3 moves along a preliminary execution function that performs control to perform preliminary grinding work and detect the position of the surface of the working area; an actual starting point that indicates the actual working area in correspondence with the teaching start point and the teaching end point, respectively, in the grinding work; an actual position data calculation function that obtains the position data of the actual end point and the actual end point; a limit calculation function that obtains a trajectory that connects the actual start point and the actual end point by a predetermined interpolation method as the work limit; It is equipped with a main execution function that performs grinding work.

Next, with reference to FIGS. 3 and 4, the operation of the grinder robot device 1 will be described by taking as an example the work of grinding a weir mark S on a workpiece W.

First, the workpiece W to be worked on is set, but this setting does not require strict precision. This is because the grinder robot device 1 actually measures the surface to be ground for each workpiece W to be worked on, so slight misalignment in setting does not pose a problem.

Next, the operator indicates the start and end points of the area where the grinder will grind. The starting point and ending point at this time do not require strict accuracy, and it is sufficient to teach the approximate position of whether or not they touch the surface of the workpiece W. Since accuracy is not required, the burden on the operator is light.

These taught start points and end points are different from the start and end points of the actual grinder grinding area, as described later, so the former are defined as the taught start point and the taught end point, and the latter are distinguished as the actual start point and the actual end point, Third
In the figure, the former are shown as P and Q, and the latter are shown as A and B.

The control device 5 detects position data for each degree of freedom of the robot 2 for positioning the tip of the grindstone 3a at the teaching start point P and the teaching end point Q. Regarding the teaching starting point P, its position data is (X _p , Y _p , Z _p , α _p ,
β _p , γ _p ), and the position data for the teaching end point Q are (X _q , Y _q , Z _q , α _q , β _q , γ _q ).

Next, the control device 5 calculates position control data that connects the teaching start point P and the teaching end point Q by linear interpolation. Since the position data for the teaching start point P and the position data for the teaching end point Q have been calculated as described above, intermediate position control data can be easily calculated using the known linear interpolation method.

Next, the control device 5 operates the robot 2 based on the position control data, but at the same time, only the degree of freedom γ that defines the angle of the grinder 3, that is, the angle of the grinding wheel 3a, is increased or decreased, and the reaction force detector 4 Reaction force control is performed so that the detected reaction force always matches a predetermined small reference reaction force.

This small reference reaction force may be set, for example, to a reaction force value that is sufficient to grind the surface of the workpiece W by about 0.1 mm (at most about 0.3 mm).

As a result, the tip of the grindstone 3a is first aligned with the teaching starting point P, then only the angle of the grindstone 3a is changed so that the tip of the grindstone 3a faces the workpiece W, comes into contact with the surface of the workpiece W at a certain position, and then The grindstone 3a enters the inside of the workpiece W very slightly while grinding the surface of the workpiece W, and when the reaction force received thereby reaches the predetermined reference reaction force, the angle change of the grindstone 3a stops.
That is, the position of the surface of the workpiece W is detected. Third
A dashed line 3a' in the figure shows the angle of the grindstone 3a at this time.

The point at the tip of the grindstone 3a is indicated by A, and this is the actual starting point where grinding is actually performed.

The position data when the grindstone 3a is at the angle indicated by the dashed-dotted line _3a ' shown in FIG. _p , Y _p , Z _p , α _p , β _p , γ _a )
is obtained as position data corresponding to the actual starting point A.

Next, the control device 5 controls the degrees of freedom X, Y, Z, α, β.
For γ, the position control data obtained by linear interpolation connecting the teaching start point P and the teaching end point Q is used, and for γ, the reaction force f detected by the reaction force detector 4 always matches the predetermined reference reaction force f ₀ . Execute grinding while increasing and decreasing the amount. As a result of this reaction force control, since the reference reaction force f ₀ is small, grinding is performed as if the surfaces of the workpiece W and the weir mark S are being stroked.

When grinder cutting is performed as described above, the degrees of freedom X, Y, Z, α, and β of the robot 2 match the position data of the teaching end point Q, X _q , Y _q , Z _q , α _q , and β _q . reach. The control device 5 reads the value of γ at this time. Letting this be γ _b , the position data (X _q ,
Y _q , Z _q , α _q , β _q , γ _b ) are obtained, which are the actual end points of the actual grinder grinding.

Next, the control device 5 performs linear interpolation connecting the actual starting point A and the actual ending point B to obtain position control data. However, in this embodiment, since the degrees of freedom X, Y, Z, α, and β are the same, it is sufficient to perform linear interpolation only for γ.

Next, the control device performs grinding using the position control data connecting the actual starting point A and the actual ending point B as the final work limit.

The grinder grinding here can be performed using any control as long as the above-mentioned work limit is not exceeded, and can be carried out using any position control, reaction force control, width control, or a combination thereof.

FIG. 4 shows changes in the reaction force f detected by the reaction force detector 4 at the initial stage of the operation.
At _t0 , the tip of the grindstone 3a is at the teaching starting point P, and at this time the reaction force f is zero. Time _t1 is when the tip of the grindstone 3a approaches the workpiece W and comes into contact with the surface of the workpiece W. Thereafter, until the reaction force f matches the predetermined reference reaction force f ₀ , the tip of the grindstone 3a enters the inside of the workpiece W, so the reaction force f increases. When the reaction force f reaches a predetermined reference reaction force f ₀ at time t ₂ , the reaction force is controlled to match this predetermined reference reaction force f ₀ from then on, so the reaction force f becomes approximately f ₀ . Maintained.

Note that the position data regarding the actual starting point A is the position data at this time _t2 .

As can be understood from the above description, the operator only needs to teach the starting point P and the ending point Q, and the teaching only needs to be done roughly, so the workload is significantly reduced compared to the conventional art. Furthermore, since the surface position of the workpiece W to be worked on is actually measured, even if there is a positional shift in the setting of the workpiece W or variations in dimensional accuracy between works of the same type, no problems will occur.

Further, the surface of the workpiece W is not etched too much, and an extremely good finished surface can be obtained.

Another example is one in which the start point and end point are connected by circular interpolation, but in this case, it is necessary to teach an intermediate point at a position between the teaching start point P and the teaching end point Q and not at the weir trace S. be.

"Effects of the Invention" According to the present invention, a robot body, a grinder held at the wrist of the robot body, a reaction force detector that detects a reaction force acting on the grinder, and a control device that controls them are provided. The control device includes a teaching input means that receives a teaching start point and a teaching end point that indicate an approximate work area from the operator, and a grinder that connects the taught teaching start point and teaching end point by a predetermined interpolation method. calculation means for calculating the position control data of the robot body such that the robot body can move, based on the position control data and performing preliminary grinding work by controlling the reaction force with a small reference reaction force, and Preliminary execution means for detecting a position; actual position data detection means for obtaining position data of an actual starting point and an actual ending point corresponding to the teaching starting point and teaching ending point, respectively, corresponding to the teaching starting point and teaching ending point during the preliminary execution; and the actual starting point. and an actual end point by a predetermined interpolation method, as a work limit, and a main execution means for executing the subsequent main grinding work so as not to exceed the work limit. A grinder work robot device is provided, which provides the following effects.

(1) A workpiece that has been grinded is not required for teaching, and a special sensor for teaching is not required.

(2) Since the workpiece to be worked on is actually measured, even if there are variations in the dimensional accuracy of the workpiece or misalignment in setting, it will not be adversely affected. In other words,
High accuracy is not required in setting the workpiece, and an extremely good finished surface can be obtained without cutting down the workpiece too much. Furthermore, since high precision is not required for teaching, the burden on the operator is significantly reduced.

(3) The operator only needs to give rough instructions and the equipment will do the rest automatically, reducing processing speed.

[Brief explanation of the drawing]

Fig. 1 is a front view of a grinder work robot device according to an embodiment of the present invention, Fig. 2 is a side view of the same, and Fig. 3 is a schematic diagram of a workpiece for explaining the weir trace grinding work by the device shown in Fig. 1. 4 are characteristic diagrams showing the relationship between reaction force and time before and after the start of work. (Explanation of symbols), 1... Grinder work robot device, 2... Orthogonal coordinate robot, 3... Grinder, 4... Reaction force detector, 5... Control device, W
...Work, S...Weir trace, P...Teaching starting point, Q...
...Taught end point, A...Actual start point, B...Actual end point.

Claims (1)

[Claims] 1. A robot body, a grinder held at the wrist of the robot body, a reaction force detector that detects a reaction force acting on the grinder, and a control device that controls them, the control device includes:
A teaching input means to which an operator teaches a teaching start point and a teaching end point indicating a rough working area, and a robot body that allows the grinder to move along a trajectory connecting the taught teaching start point and teaching end point by a predetermined interpolation method. a calculation means for calculating position control data; a preliminary execution means for detecting the position of the work area surface by performing preliminary grinding work based on the position control data and performing reaction force control with a small reference reaction force; During the preliminary execution, an actual position data detecting means for obtaining position data of an actual starting point and an actual ending point indicating an actual work area corresponding to the teaching starting point and teaching ending point, respectively; and a predetermined interpolation between the actual starting point and the actual ending point. 1. A grinder work robot apparatus comprising: a limit calculation means for obtaining a working limit based on a trajectory connected by a method; and a main execution means for executing the subsequent main grinding work so as not to exceed the work limit.