JPH03196959A - Surface polishing method of abrasive robot - Google Patents

Abstract

PURPOSE:To enable it to polish the whole polished surface of a work with a constant cutting allowance at all times by adjusting the extent of pressing force being given to a working tool in response to a relative position with a polishing range circumferential part as grasping a positional relationship between the polishing range circumferential part and the working tool. CONSTITUTION:A polishing range 9a is polished by a first abrasive tool 7 in keeping up constant pressing force as measuring a distance between a circumferential part 9b of this polishing range 9a and the first abrasive tool 7. Next, the abrasive tool is replaced with a second small abrasive tool, the polishing range 9a is polished by this second abrasive tool in controlling the pressing force of the second abrasive tool by a controller 10 so as to make reaction larger in proportion as making a distance between the circumferential part 9b of the polishing range 9a and the second abrasive tool smaller, as measuring the distance between the circumferential part 9b of the polishing range 9a and the second abrasive tool.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a surface polishing method using a polishing robot, and particularly to a polishing method used in mold polishing work, etc., configured using a force control robot or a force control table. The present invention relates to a flat surface polishing method for a polishing robot that improves the flatness of the polishing range by polishing the outer periphery of the polishing range set on the flat surface of the robot with good accuracy.

[Conventional technology]

Recent advances in NC machine tools, welding robots, and the like are remarkable, and automation of various tasks is progressing using these tools. However, on the other hand, automation tends to be delayed, for example in the polishing work of molds. This is because when working with normal NC machine tools or welding robots, work can be carried out by simply controlling the position and speed, but in polishing work, controlling the position and speed alone is not sufficient, and the amount of force must be controlled. This is because the work cannot be executed automatically. That is,
Controlling only the position and speed causes wear of the grinding wheel and errors between the taught tool trajectory and the actual workpiece position, which may cause the tool to be pressed too strongly against the workpiece, or the tool may The work may be incomplete due to separation from the staff, and complete automation cannot be achieved.

In order to overcome such problems and achieve automation of polishing work, Japanese Patent Application Laid-Open Nos. 60-207769 and 63
A polishing device according to No. 2659 has been proposed. JP-A No. 60-207769 discloses a polishing tool in which a permanent magnet is disposed close to a grindstone, a magnetic circuit is formed between the workpiece and the grindstone, and the grindstone is pressed against the workpiece by magnetic attraction. are doing. In addition, JP-A No. 63-2659 generally states that when a grinding wheel is fed at a constant speed during polishing, the surface pressure of the grinding wheel (the value obtained by dividing the force pressing the grinding wheel against the workpiece by the contact area between the grinding wheel and the workpiece) Based on the empirical knowledge that the cutting volume of the workpiece is approximately proportional to the cutting volume, the grinding wheel is supported by a pneumatic cylinder, and the air pressure supplied to the pneumatic cylinder is controlled at a constant level to maintain a constant force pressing the grinding wheel against the workpiece. discloses a polishing machine that performs uniform polishing.

[Problem to be solved by the invention]

In the configuration of the polishing tool disclosed in Japanese Patent Application Laid-Open No. 60-207769, if the workpiece is a non-magnetic material, no magnetic attraction force is generated, so polishing cannot be performed, and the force generated by magnetism makes it impossible to perform the polishing operation. has the problem of not being able to obtain power. On the other hand, JP-A-63-2
No. 659 can eliminate the above-mentioned problems in JP-A No. 60-207769. However, according to the structure of JP-A No. 63-2659, as shown in FIG. 7, for example, the grindstone 100 moves in the direction A to the outer circumference 102 of the polishing range 101 while maintaining a constant cylinder pressure and constant speed. Thereafter, the workpiece 103 is polished by moving in the B direction while maintaining a constant cylinder pressure and constant speed. Now, 100 whetstones
(length) is divided into, for example, n equal parts and a small grindstone G, ~
G, the depth (depth of cut) di(X) of the workpiece 103 to be ground by the grindstone G1 is expressed by the following equation.

d 1 (x) = (f/S) a/n However, X≧0 Here, the pressing force caused by f Nijilinda pressure is force S: Grinding wheel bottom area α: proportionality constant Figure 8 illustrates this state. (a).

In FIG. 8(a), the horizontal axis represents x and the vertical axis represents di(x).

Next, the depth of cut d2(x) produced by the grindstone G2 is expressed by the following formula.

In the case of X≧L/n, dz (x) = (f/S) a/n In the case of x<L/n, d2 (x)=.

This is similarly shown in FIG. 8(b).

Repeat the above operation n times to obtain di(x) to d.

By finding all of (X) and adding them together, the grindstone 10
The depth of cut d (x) for the entire 0 is determined by the following equation.

d(X)=d1 (x)+d2 (X)+・・・・・・
+d,,(x) This is shown in a diagram as shown in FIG. 8(C). As is clear from this figure, the depth of cut is constant when X≧L, but
For x x L, the depth of cut decreases as X becomes smaller. Therefore, when the workpiece 103 is polished at a constant cylinder pressure and a constant feed rate, the outer peripheral part 1 of the polishing range 101
In 02, a problem occurs in that the depth of cut decreases.

This means that, as shown by the broken line in FIG. 7, there is always insufficient machining allowance at the outer periphery of the polishing range. When insufficient machining allowance occurs on the polished surface, cutting marks caused by pre-processing such as milling remain, and the resulting product becomes extremely aesthetically unsightly.

For this reason, in the conventional polishing apparatus disclosed in Japanese Patent Application Laid-Open No. 60-2659, it is necessary to correct the cutting allowance at the outer periphery of the polishing range after the polishing operation is completed.

An object of the present invention is to provide a flat surface of a polishing robot that, when polishing a flat surface of a member to be polished, allows the machining allowance of the surface to be polished at the outer periphery of the polishing range to be the same as the machining allowance of other surfaces to be polished. The object of the present invention is to provide a polishing method.

[Means to solve the problem]

In the first surface polishing method for a polishing robot according to the present invention, when a polishing operation is performed in which a polishing tool is pressed against a workpiece to be polished, the polishing tool receives a reaction detected by a force sensor provided at the hand. In the polishing method of a polishing robot, which sets the force and executes the polishing work, the position and pressing of the polishing tool is determined based on the force and the relative position of the polishing tool and the workpiece detected by the output signal of the position sensor. Provide data on the polishing range and polishing path on the polishing member, first prepare a first polishing tool as the polishing tool, and measure the distance between the outer circumference of the polishing range and the first polishing tool. Polish the polishing area with a constant pressure with the polishing tool, then replace the polishing tool with a smaller second polishing tool, and measure the distance between the outer periphery of the polishing area and the second polishing tool. At the same time, the pressing force of the second polishing tool is changed so that the reaction force increases as the distance between the outer periphery of the polishing range and the second polishing tool becomes smaller. It is characterized by being polished.

Second surface polishing method for a polishing robot according to the present invention When a polishing operation is performed in which a polishing tool is pressed against a workpiece to be polished by the pressing action of a pressure cylinder, the polishing tool and workpiece detected by the output signal of a position sensor are used. In a polishing method for a polishing robot that executes a polishing operation by setting the position of a polishing tool and the pressure supplied to a pressure cylinder based on the relative position of a polishing member, the present invention provides data on a polishing range and a polishing path on a member to be polished; First, prepare a first polishing tool as a polishing tool, and while measuring the distance between the outer circumference of the polishing area and the first polishing tool, polish the polishing area with the first polishing tool while keeping the pressure constant. Then, replace the polishing tool with a smaller second polishing tool, and while measuring the distance between the outer periphery of the polishing area and the second polishing tool, use the second polishing tool to cover the polishing area. It is characterized in that polishing is performed by changing the pressure so that it increases as the distance between the outer peripheral part and the second polishing tool becomes smaller.

[Effect]

According to the first and second aspects of the present invention, in both cases, the polishing process is divided into two steps, and in the first polishing process, a large polishing tool is used to polish the surface to be polished, and in the next polishing process, the surface to be polished is polished using a large polishing tool. In the polishing process, a small polishing tool was used to particularly polish the outer periphery, so that the cutting allowance on the polished surface of the outer periphery was the same as that of other polished surfaces such as the center.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 to 3 show a first embodiment of the surface polishing method according to the present invention, FIG. 1 is a schematic diagram showing the main part configuration of a polishing robot, FIG. 2 is a configuration diagram of the electrical system, and FIG. The figure is a flowchart showing the procedure of a surface polishing method. Reference numeral 1 denotes a multi-joint polishing device, which has a plurality of arms 2.3, and position sensors 4, 5 are installed at the joints that connect these arms.
and a drive device (not shown). Reference numeral 6 denotes a force sensor provided at the tip of the hand, and a working tool 8 having a grindstone 7 is attached to the tip of the sensor 6.

Reference numeral 9 indicates a workpiece that is a member to be polished, 9a indicates a surface to be polished in the workpiece 9, and 9b indicates an outer circumference (boundary line) of the polishing range. The grindstone 7 is arranged so that its bottom polishing surface faces the polished surface 9a of the workpiece 9. The work tool 8 can polish the workpiece 9 by rotating or vibrating the grindstone 7.

The grindstone 7 is set on the workpiece 9 at a predetermined polishing start position away from the outer circumference 9b of the polishing range, and then its position is controlled so that it moves in the A direction while polishing the surface to be polished 9a.

10 is a controller that instructs the polishing apparatus 1 to perform a required polishing operation. The reaction force applied from the workpiece 9 to the power tool 8 during the polishing operation is detected by the force sensor 6, and the output signal 11 of the force sensor 6 is fed back to the controller 10. Similarly, output signals 12 from the plurality of position sensors 4, 5, etc. are fed back to the controller 10, and the position of the working tool 8, that is, the grindstone 7, can be known from these position detection signals. On the other hand, the controller 10 adjusts the position of the grinding wheel 7 based on the reaction force detection signal 11 and position detection signal 12 input by feedback, as well as the control calculation program and workpiece shape information prepared in advance in the internal storage section. The force of the grindstone 7 against the workpiece 9 is calculated and processed to a required value, and the command value obtained as a result is sent to each drive device of the polishing apparatus 1 as a drive command signal 13.

Reference numeral 14 denotes an operation unit used by the operation operator to store data required for the polishing operation or a program regarding the procedure of the polishing operation in the storage unit of the controller 10. Reference numeral 15 denotes a display unit for providing information from the controller 10 side to the operator regarding the calculation/processing results or the progress of the work as necessary.

Controller 1 in the polishing robot shown in FIG.
The block diagram of FIG. 2 shows only the configuration of the electrical system including 0. In FIG. 2, 20 is a group of a plurality of position sensors including the position sensors 4 and 5. 6 is the force sensor.

Reference numeral 21 denotes a group of a plurality of drive devices arranged at appropriate locations on each arm. Further, 14 is the operation section, and 15 is the display section. The controller 10 includes an input/output section 22 forming an interface function, an arithmetic section 23, and a control section 2.
4 and a storage section 26.

The storage unit 26 stores a program for executing a surface polishing method to be described later.

Detection signals from the position sensor 20 and force sensor 6, operation signals input by the operator from the operation unit 14, and various data are sent to the CPU 25 via the input/output unit 22.
The CPU 25 calculates and processes these data and a control/calculation program prepared in advance, and the resulting data is stored in the storage unit 26 as necessary.
Furthermore, the drive device 21 or the display section 15 is connected via the input/output section 22.
will be sent to

The surface polishing method executed by the polishing robot having the above configuration will be explained based on the flowcharts shown in FIGS. 1, 2, and 3.

In FIG. 3, in the first step 31, the workpiece 9
Input and set the polishing range to be polished and the polishing path of the grindstone 7 during polishing. Information on the polishing range and polishing path is normally input by an operator via the operation unit 14. The input information such as the polishing range is stored in the storage unit 26.

As another setting format, for example, the controller 1o may be configured to be provided with information such as the polishing range for each polishing operation from a host computer that manages all polishing operations. Next, the controller 10 creates command values for position, speed, and force for each drive device 21,
Polishing is performed by outputting a drive command signal based on these command values (steps 32 and 33). In this polishing operation, the grindstone 7 is first set at the polishing start position above the workpiece 9, and the distance between the outer circumference 9b of the polishing range and the tip 7a of the grindstone 7 is set as a variable as shown in FIG. 4(A). Set as X (step 32).

The value of this variable X changes as the position of the grindstone 7 changes. Thereafter, polishing work is started according to the polishing range set in step 31 (step 33).

In the polishing operation, as shown in FIG. 4(A), a force F is applied to the grindstone 7 by a drive device (not shown), and the tip 7a of the grindstone moves along the polishing path onto the surface to be polished 9a. It moves in the A direction until it overlaps with the outer peripheral part 9b of the polishing range, and then changes the moving direction and moves in the B direction. In this embodiment, the length dimension of the grinding wheel 7 in the advancing direction is L
', and as described above, the distance between the tip 7a of the grindstone 7 and the outer circumference 9b of the polishing range is set as X. In the grindstone 7 where the polishing work is performed in such a state, the pressing force F applied to the grindstone 7 is determined according to the position of the grindstone 7 with respect to the outer circumference 9b of the polishing range, that is, the distance X. It is controlled as follows based on the command signal.

X≧O: F=F.

X<0: F=0 Polish all the polishing areas under these conditions Step 34.
35), the operation is temporarily stopped after the entire polishing range has been polished (steps 34 and 36). Next, the grindstone is replaced with a smaller one (not shown), and the pressing force shown in FIG. 4(B) is applied to the surface to be polished around the outer circumferential portion 9b, and the second polishing operation is started again. (Step 37).

In this polishing work, the pressing force is controlled so as to satisfy the following conditions. This condition is a formula representing the characteristics shown in FIG. 4(B).

0≦X≦L': F=-K (X-L") However,
F2 when X=0 F1 when X=L'X>L' :F=O , and in step 38
Polishing is performed by determining the pressing force according to the above formula while determining the range of . That is, when 0≦X<L', the depth of cut correction is controlled (step 39), and when X>L', F is set to 0 to prevent over-cutting, and when X<0, the polishing range is exceeded. to finish the polishing work.

Figure 4 (B) shows the polishing characteristics in the depth of cut correction work.
Here, the position of the outer circumferential portion 9b of the polishing range is set as the origin. In the depth of cut correction amount control, the pressing force F increases linearly as the grindstone approaches the outer circumference.

In addition, when controlling the above-mentioned surface polishing work, the controller 10 moves the work tool 8 at a required constant speed and changes the position of the work tool 8 to a required position. The premise is that the required pressing is controlled by applying force.

Therefore, the controller 10 sequentially performs the following in real time:
Each command value of position and force is rewritten and determined, and these command values are converted into a drive signal 13 for driving each drive device 21 to operate each drive device.

Next, a second embodiment of the present invention will be described based on FIGS. 5 and 6. 51 is an articulated polishing device consisting of arms 2, 3, etc.; 8 is a work tool Z9 having a grinding wheel 7 at its tip; 10 is a controller; 14 is an operation tool; 15 is a display section. The polishing device 51 is provided with a plurality of position sensors and drive devices (not shown), and a detection signal 12 from the position sensor is fed back to the controller 10, and a drive command signal 13 is sent from the controller 10 to each drive device.

The above configuration is basically the same as the first embodiment shown in FIG. Further, the polishing device 51 includes a cylinder 52 at the tip of the arm 3 that is operated by hydraulic or pneumatic pressure supplied from a pressure source (not shown), and the working tool 8 is attached to the tip of the cylinder 52.

In the polishing device 51 having such a configuration, force F is generated by pressure applied by the cylinder 52 when pressing the grindstone 7 during polishing work. Further, a control signal 53 for adjusting the pressure supplied to the cylinder 52 is given from the controller 10 to the cylinder 52, and the pressure given to the power tool 8 from the cylinder 52 is controlled by this control signal 53.

In the polishing method according to the second embodiment described above, the first grindstone 7 and The press controls the force for each of the smaller wheels that are then replaced. Therefore, the method of giving the command value that determines the pressing force during polishing is exactly the same as in the first embodiment. However, in the case of this embodiment, a hydraulic or pneumatic cylinder 52 is used to generate force for pressing the grindstone 7, so pressure control is used instead of F, F, , F2 in the above equation. Using the signal P and its predetermined values PI and P2, X<O and X>L'
In the range of , the pressure control signal P is configured to give a predetermined value Pl (<o) instead of F=0. That is, in the range of Xku0 and X>L', a negative command value P3 is given as a pressure control signal, and the cylinder 52 is contracted so that the grindstone and the workpiece 9 do not come into contact after polishing is completed.

FIG. 6 is a graph in which the distance X is plotted on the horizontal axis and the pressure value P of the control signal 53 is plotted on the vertical axis.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, in a polishing robot that automatically performs polishing work that requires force control, the surface to be polished of the workpiece to be polished is flat, and the polishing range is In the case of the center part of the workpiece, we have realized a polishing method that can adjust the force applied to the work tool according to its relative position to the outer circumference of the polishing area while grasping the positional relationship between the outer circumference of the polishing area and the work tool. As a result, the entire surface of the workpiece to be polished can be polished with a constant cutting allowance.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the configuration of a polishing robot to which the surface polishing method of the present invention is applied, FIG. 2 is a block diagram showing the configuration of the electrical system, and FIG. 3 is a first embodiment of the surface polishing method. Flowchart, FIG. 4 is a diagram explaining the situation of flat surface polishing work, FIG. 5 is a schematic diagram showing a polishing robot having another configuration to which the second embodiment is applied, and FIG. 6 is a diagram illustrating the flat surface polishing method. Characteristic diagrams showing pressure changes in the second embodiment, FIGS. 7 and 8 are diagrams for explaining problems in the conventional surface polishing method. [Explanation of symbols] 1.51... Polishing device 2.3... Arm 4.5.20... Position sensor 6... Force sensor 7.100. ... Grindstone 8 ... Work tool 9 φφ ... Workpieces 9a, 101 ... Surface to be polished 9b ... Polishing range outer periphery 10 ... ... Controller 14 ..... Operation section 15 ..... Display section 25 .... CPU 26 ..... Memory section 52 ....・Hydraulic or pneumatic cylinder Figure 4 Figure Δ Figure 7

Claims (2)

[Claims] (1) When a polishing operation is performed in which a polishing tool is pressed against a workpiece to be polished, the reaction force received by the polishing tool is detected by a force sensor installed at the tip of the hand, and the output signal of a position sensor is detected. In the polishing method for a polishing robot, the position and pressing force of the polishing tool are set based on the relative positions of the polishing tool and the member to be polished, and the polishing operation is performed by setting the position and pressing force of the polishing tool based on the relative position of the polishing tool and the member to be polished. First, a first polishing tool is prepared as the polishing tool, and while measuring the distance between the outer periphery of the polishing range and the first polishing tool, Polish the polishing area while maintaining a constant pressing force, then replace the polishing tool with a small second polishing tool, and measure the distance between the outer periphery of the polishing area and the second polishing tool. 2
The polishing tool is used to polish the polishing area between the outer periphery of the polishing area and the second
A surface polishing method for a polishing robot, characterized in that polishing is performed by changing the pressing force of a second polishing tool so that the reaction force increases as the distance from the second polishing tool decreases. (2) When polishing is performed by pressing a polishing tool against a workpiece to be polished by the pressing action of a pressure cylinder, based on the relative position of the polishing tool and workpiece detected by the output signal of a position sensor. In the polishing method for a polishing robot, which sets the position of the polishing tool and the pressure supplied to the pressure cylinder and executes the polishing operation, data on the polishing range and polishing path on the member to be polished are provided, and the A first polishing tool is prepared as a polishing tool, and while measuring the distance between the outer periphery of the polishing range and the first polishing tool, the pressure is kept constant over the polishing range with the first polishing tool. Polishing, then replace the polishing tool with a small second polishing tool, and while measuring the distance between the outer periphery of the polishing range and the second polishing tool, polish the polishing range with the second polishing tool, A surface polishing method for a polishing robot, characterized in that polishing is performed by changing the pressure so that it increases as the distance between the outer periphery of the polishing range and the second polishing tool becomes smaller.