JPH04306704A - Deburring and chamfering method for force control robot - Google Patents

Abstract

PURPOSE:To execute work which satisfies the finish precision of deburring and chamfering by separating work into two steps even in the case of a casting which has comparatively large burrs and dimension deviation. CONSTITUTION:When a force control robot which can simultaneously control a position and force executes the deburring and chamfering of the case which has the comparatively large burrs and dimension deviation at the same time, work is separated into the two steps. In a first step, rough working is executed with position control, and finish working is executed with specified pressure control in a second step.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for burring and chamfering castings having relatively large burrs and dimensional deviations.

0002

2. Description of the Related Art In the case of a casting with a relatively small burr, it has been possible to eliminate the burr and chamfer by controlling a constant pressing force even if there are dimensional deviations or teaching errors of the casting itself.

0003

However, castings with relatively large burrs have the following problems.

(1) If only a constant pressing force is controlled, if the set pressing force is small, the set pressing force will be reached at the burr itself, making it impossible to process the part to be chamfered.

(2) If the set pressing force is set to a large value in accordance with large burrs, the casting itself will be damaged because the burrs are irregular in size.

[0006] In order to solve the above problems, the present invention aims to provide a method for burring and chamfering in two stages: one using only position control and the other using constant pressing force control. shall be.

[0007]

[Means for solving the problem] A processing tool is installed in the robot body via a force sensor, and a control device performs position control in the feeding direction of the processing tool, and force control in the pressing direction of the processing tool. In this method, the rough machining of the burr and chamfering work is performed by position control in the first step, and the second step is by using a constant pressing force. Finishing is done under control. Furthermore, the position control in the first stage uses automatically generated route data based on the route data taught for performing the force control in the second stage.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be explained in detail with reference to the drawings. FIG. 2 is a block diagram for implementing the present invention. 1 is a robot arm, and a processing tool 2 consisting of a tool body and a tool holder is installed at the tip via a force sensor 3, and 4 is a reduction mechanism 5.
A servo motor drives the robot arm 1 via the servo motor 1, and 6 is an encoder that detects the position of the servo motor 4.

The control device 7 includes an arithmetic device 8 and an arithmetic device 8.
A storage device 9 is provided to store the data processed by the encoder 6, and the signal from the encoder 6 is sent to the control device 7, and the processed data is used to control the servo motor via the servo amplifier 10. 4, the machining tool 2 is moved to the taught position,
Make burrs and chamfers depending on the posture. In addition, by sending signals from the encoder 6 and force sensor 3 to the control device 7 for calculation processing, the machining tool 2 maintains a constant pressing force against the casting at the taught position and posture, and eliminates burrs. Make a chamfer. In this way, the signal from the force sensor 3 can be used to switch between control modes of only position control and simultaneous control of position and force.

FIG. 3 is a schematic diagram of a casting having relatively large burrs and dimensional deviations. Aluminum wheels are examples of such castings. ■ is the reference position of the casting determined from the teaching data. In Fig. 3, the position of the casting and the reference position of the casting match, but due to dimensional deviations of the casting, teaching errors, etc., the position of the casting and the reference position of the casting An error occurs between the reference position and the reference position. ■ is the position where the final finishing machining is performed in the second stage of this example; ■ is the maximum burr size ■ that allows for dimensional deviation of the casting and allows finishing machining by controlling a constant pressing force. The position where the rough machining performed in the first stage of this embodiment is performed is shown.

This embodiment can be realized by teaching the route data of (1) and (2), respectively. However, in order to teach the route data of ■, manual processing is required to reach the burr state of ■, and it is inefficient to teach the route data twice along with the route data of ■. be. Therefore, the route data for ■ is
Automatic creation using force control based on route data. The procedure for this method will be explained based on FIG. 4 and FIG. 1.

(1) First, path data necessary for performing the second stage constant pressing force control is taught. In this path data teaching, in addition to the positional teaching points P1 to P5, the direction in which the machining tool is to be pressed is also taught. Specifically, at arbitrary positions F1 to F4 between the respective teaching points, press the tip of the processing tool directly against the workpiece in the desired direction with an arbitrary force, and at this time, the force sensor detects the force. The direction cosine is calculated from the component forces in the three axial directions and stored in the storage device. With the teaching method described above, during playback, it is possible to cause the machining tool to follow the workpiece while controlling the pressing force at a constant level in the taught direction in each section.

(2) Next, the first stage of automatic generation of route data is performed. This is done by simultaneously controlling the position and force based on the teaching point created in (1), performing regenerative operation of the robot while applying a constant pressing force to the workpiece, and reproducing the robot's trajectory (represented by the ● mark). ), a position (represented by a circle) shifted by a specified amount in the opposite direction to the pressing direction is stored in the storage device of the control device at every time synchronized with the sampling period of force control.

This method will be explained in detail with reference to FIG. TP1 and TP2 are position teaching data, and the processing tool moves from TP1 to TP2 by linear interpolation. At this time, the current position P(PX
, PY, PZ) in the position control direction from the target value Pp (Pp
X, PpY, PpZ) and the target value Pf (P
fX, PfY, PfZ). The calculation of Pp is
This is done using the general reproduction method using the teaching points of TP1 and TP2.

Regarding Pf, the speed command is calculated based on the deviation between the force generated between the processing tool and the workpiece detected by the force sensor and the set pressing force indicating the magnitude of the pressing force. Given as a value. Using Pp and Pf obtained in this way, the calculation shown in equation (3) is performed and the current position is updated every sampling period of force control, thereby achieving constant pressing force control. At this time(
4) As shown in formula (3), calculate the position P1 (P1X, P1Y, P1Z) that is shifted by a specified amount Pk (PkX, PkY, PkZ) in the escape direction of force control from the value calculated by formula (3), and The encoder values for each axis of the robot obtained by the coordinate transformation calculation are stored in a storage device. PX = PX + PpX
+ PfX PY = PY
+ PpY + PfY
(3) PZ
= PZ + PpZ + PfZ

PX1= PX + PpX +
PfX − PkX
PY1=PY+Pp
Y + PfY − PkY (4)
PZ1= PZ + P
pZ + PfZ − PkZ
By allowing the dimensional error of the casting and setting the predetermined amount Pk to a size up to the finish-machined portion, rough machining by position control in the first stage can be performed.

By the method described above, in the first stage, rough machining is performed using the data created in (2) in one teaching, and in the second stage, the rough machining is performed using the data created in (2).
In step (1), the teaching data created in step (1) is used to perform finishing machining with constant pressing force control.

According to the present invention, even if a casting has relatively large burrs and dimensional deviations, burrs and chamfers can be removed by constant pressing force control, and finishing accuracy can be satisfied.

[Brief explanation of drawings]

[Fig. 1] Flowchart diagram of the present invention

[Figure 2] Configuration diagram for implementing the present invention

[Fig. 3] A schematic diagram showing a casting having relatively large burrs and dimensional deviations, which is the object of the present invention.

[Fig. 4] Conceptual diagram of a method for automatically generating route data used in the first step of the present invention

[Figure 5] Specific diagram of a method for automatically creating route data used in the first step of the present invention

[Explanation of symbols]

1 Arm 2 Processing tools 3 Force sensor 4 Servo motor 7 Control device 8 Arithmetic device 9. Storage device

Claims (2)

[Claims] 1. A processing tool is provided on the robot body via a force sensor, and a control device performs position control in the feeding direction of the processing tool, and performs force control in the pressing direction of the processing tool, In the method of burring and chamfering castings with relatively large burrs and dimensional deviations, the first step is to perform rough machining of burrs and chamfering using position control, and the second step is
A method for burring and chamfering in a force-controlled robot, characterized in that finishing is performed by force control with constant pressing in each step. [Claim 2] The position control in the first stage is based on the path data taught to perform the force control in the second stage.
A burr and chamfering method in a force-controlled robot according to claim 1, which uses automatically generated path data.