JPH0577151A - Multispindle freedom device - Google Patents

Abstract

PURPOSE:To provide an automatic machining device fit for machining the surface with free curved surface, especially for deburring, grinding, and the like. CONSTITUTION:In a head with a rigid body provided at the tip of an arm 10, a grinder 1 is installed through a force sensor 6 provided at the head front part and a member with vibration absorbing function provided at the head rear part so as to form such a structure as to be in control of enabling previous copying with a little noise at the time of copying the curved surface in the automatic grinding of the machined surface with free curved surface. A cup type grinding wheel provided through a flexible joint 2 is used for the grinder 1 formed to have such mechanism as to press the grinder body mechanically to the machined surface by a damper 7. With this structure of performing the previous copying of the machined surface by the force sensor 6, the generation of delay in a control system and an action system is eliminated to obtain the ground surface of high quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to processing of a surface having a free curved surface, and more particularly to a multi-axis degree-of-freedom device such as deburring and grinding.

[0002]

2. Description of the Related Art Conventionally, for automating operations such as deburring and grinding, a robot or an automatic device has been used as means for copying and grinding an indefinite shape. That is, it is a method of sequentially teaching a machining path and a machining posture to such a robot or an automatic device for each machining point by a teaching playback method, and automatically grinding according to the teaching point. Further, recently, as shown in FIG. 3, a robot arm 15 having a grinding tool 17 attached to the tip thereof via a force sensor 16 is known. This is to control the reaction force N from the position and the pressing force F obtained based on the information from the force sensor 16 and other information, and to automate the deburring and grinding work on the machined surface 19 using the grindstone 18. Is the way.
(Japanese Patent Laid-Open No. 1-222311).

[0003]

However, in the teaching playback system in the prior art, it is necessary to teach the machining position and the grinding angle of the grinding tool with respect to the machining surface. Therefore, the teaching method becomes very complicated, and accordingly, a large proportion of work is required for teaching time. In addition, the force sensor 1 is attached to the tip of the robot arm 15.
In the case of a grinding robot having a grinding tool coaxially through 6, the reaction force N of the pressing force F received from the machining surface is transmitted to the robot control system, and the robot is controlled so that the set reaction force N is achieved. However, since it has a function of making the pressing force F of the grindstone 18 constant, when automatically grinding a flat surface or a curved surface having a fixed curvature, grinding can be performed while sequentially moving to the taught position. However, in this grinding robot, if the reaction force N received by the grindstone processing unit is not accurately transmitted to the force sensor 16,
Since an error occurs in the control system of the robot, the force sensor and the grinding tool are one rigid body. However, with such a structure, in the case of grinding when the machined surface is a free-form surface and has local unevenness, when the machined surface is detected by the force sensor 16, grinding is performed coaxially with the force sensor 16. Since there is the grinding tool 17, a delay time occurs in the copying control from when the grindstone 18 senses the processing point to when the processing point is ground. In addition, since it is easily affected by the natural vibration of the grinding tool body generated at the time of grinding and noise such as grinding resistance, there are some problems in terms of stable grinding.

Further, as shown in FIG. 3, a flat grindstone 18 is used for grinding work.
When the (offset grindstone) is used, the contact area is small, so that it is difficult to stabilize the grinding ability unless delicate load control is performed. Moreover, since the contact area of the grindstone contacting the processed surface differs between the grindstone in the initial stage before grinding and the grindstone that has been polished to some extent, the grinding ability varies under a constant pressing force. In order to stabilize it, a grindstone in a pre-polished state was used to deal with it.

Therefore, an object of the present invention is to provide a multi-axis degree-of-freedom device capable of obtaining a high-quality ground surface by stable copying control in the automation of grinding work for an indefinite shape such as a free-form surface. is there.

[0006]

Means for Solving the Problems A surface state at a plurality of machining points which is taught in advance is detected by a force sensor, and a grinding tool is controlled on the basis of this information, while following a path formed by the plurality of machining points. In a multi-axis degree-of-freedom device that performs curved surface processing, a force sensor is provided separately from a grinding tool in a front direction of a path along which the grinding tool moves.

Further, in such a multi-axis degree-of-freedom device, a grinding tool is attached via a member having a vibration absorbing function and / or an elastic body for controlling a pressing force, such as a spring or a damper. Also, the grinding portion of the grinding tool is attached by a flexible joint. Furthermore,
The grinding part of the grinding tool is cup-shaped.

[0008]

By disposing the force sensor separately from the grinding tool in the front of the movement path, the machining point is followed in advance, that is, the surface condition of the machining point is detected prior to the machining, and it is performed based on the information obtained in advance. It becomes possible to perform the copying control, and the time delay of the above-described conventional copying control,
That is, it is possible to eliminate the deviation between the processing point for which the surface state information is obtained and the processing point that is actually processed.

Further, as a result of such a separated arrangement, the influence of the natural vibration of the grinding tool and the noise generated from the grinding resistance on the force sensor can be made smaller, and more accurate copying control becomes possible. ing. The suppression of the influence of the vibration of the grinding tool on the force sensor can be made more effective by interposing the vibration absorbing function member in the attachment of the grinding tool.

Further, since the pressing force of the grinding tool is mechanically controlled by an elastic body, it is possible to deal with a machining surface which is constantly changing evenly. Furthermore, in addition to the mechanical control, the cup type By using a flexible joint as the joint between the grindstone and the grinder, it has become possible to obtain a high-quality ground surface even on a machined surface with an irregular shape.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The multi-axis degree-of-freedom device has a rigid body to which a guide roller 5 is attached via a force sensor 6 at a front end portion of a frame 8 attached to a joint portion 9 of an arm 10 thereof. Further, the grinder 1 is attached to the rear end of the frame 8 via the vibration-proof pad 14 and the damper 7. Further, the grinder 1 has a cup-shaped grindstone 3
Are attached via the flexible joint 2.
In such a multi-axis degree-of-freedom device, the guide roller 5
The reaction force N received from the work surface 12 is detected by the force sensor 6 in the normal direction Z, and is analyzed by the control unit, for example, as in the above-mentioned conventional technique. Then, the data is transmitted to the operation control unit of the arm 10, and based on this, the arm 1
0 is inclined in the normal direction Z, and the required grinding angle is obtained. Here, since the grinder 1 is operating at a constant grinding speed V, the processing point P ₁ moves to P ₂ after L / V. Therefore, the state of the curved surface analyzed in P ₁ is temporarily stored in the control unit, and the arm 10 is operated after L / V. Therefore, it is possible to faithfully execute the processing conditions at the processing point without causing a time lag between the detection of the processing point and the processing therefor as in the above-mentioned conventional technique, and more accurate processing can be performed. Also, grinder 1
However, since it is mechanically controlled through the damper 7, it can smoothly follow the machining surface 12 that changes every moment, and
The cup-shaped grindstone 3 is also protected, and a stable and constant pressing force F is always obtained against the processed surface 12. Furthermore,
Since the cup-shaped grindstone 3 is gripped via the flexible joint 2, the followability is further enhanced. Furthermore, since the grinder 1 is attached to the frame 8 via the anti-vibration pad 14, noise generated during grinding does not directly affect the frame 8, so that the force sensor 6 detects the reaction force N. Will be more accurate.

Next, an embodiment of a method for polishing the surface of an impeller (FIG. 4) using the apparatus according to the present invention will be described in detail with reference to FIGS. 1, 2 and 4. As shown in FIG. 4, the impeller has five blades 11 having a free-form surface on the outer peripheral surface of a truncated cone.
It is a cast article having a shape having a to 11e. Therefore, the machined surface becomes a cast surface, which is a surface state having local irregularities and indeterminate waviness in addition to a free-form surface. How to polish the impeller surface 12 having these conditions will be described. Several teaching points 20 are displayed on the grinding path of one blade (impeller 11a) from the grinding start point to the grinding end point. When the cup-shaped grindstone 3 approaches the taught work starting point 20-1, the guide roller 5 comes into contact with the work surface 12. At that time, the force sensor 6 is operated for analysis, and the inclination with respect to the normal direction Z is set. Then, the analysis value is transmitted to the control unit of the multi-axis degree-of-freedom device for analysis, the result is transmitted to the operation control unit of the arm 10, and the arm 10 is tilted in the normal direction, whereby the frame 8 is moved to the normal Tilt in direction Z,
A constant grinding angle is fixed. Then, the grinder 1 is driven and the cup-shaped grindstone 3 is rotated to be in a grinding preparation state.

When the grinding process is started, the force sensor 6 acts up to the next teaching point 20-2 while maintaining a constant grinding angle without receiving noise generated during grinding, while the arm 10 is moved forward. Grinding is performed under the grinding conditions input to the control unit. As a mechanical control at that time, the cup-shaped grindstone 3 via the flexible joint 2 freely suppresses the slight unevenness of the casting surface and indeterminate waviness, and moreover, the cup-shaped grindstone 3 for the work surface 12 is controlled. The pressing force F of is controlled by the damper 7. Under the mechanism controlled as described above, grinding is performed up to the final teaching point 20-n, and the grinding of one impeller 11a is completed.
The remaining four impellers are automatically ground by the same operation, and the work is completed.

[0014]

As described above, according to the present invention, the force sensor for detecting the information about the machining point is provided separately from the grinding tool, and the mechanism for preceding is used, so that the control system and the operation system are provided. It has become possible to perform control without causing a delay. Also, by installing the grinding tool via a damper having an absorbing function, noise generated from the grinder grinding can be absorbed, and the copy analysis capability is improved.
With these, it has become possible to obtain a higher quality ground surface.

[Brief description of drawings]

FIG. 1 is an external view of a head portion of a multi-axis degree-of-freedom device showing an embodiment of the present invention.

FIG. 2 is a side view of the grinding head of FIG.

FIG. 3 is an external view of a head unit of a conventional grinding robot.

FIG. 4 is an external view of a work targeted by the apparatus of the present invention.

[Explanation of symbols]

 1 Grinder (grinding tool) 2 Flexible joint 3 Cup grindstone (grinding part) 6 Force sensor 7 Damper (elastic body) 10 Arm

Claims (5)

[Claims] 1. A plurality of force sensors for detecting information about surface states at a plurality of machining points that are taught in advance are provided. While controlling the grinding tool based on the information obtained by the force sensors, a plurality of force sensors are provided. In a multi-axis degree-of-freedom device that processes curved surfaces according to the path of the machining point, the force sensor is provided separately from the grinding tool in the forward direction of the movement path of the grinding tool so that the machining point can be followed in advance. A multi-axis degree-of-freedom device. 2. The multi-axis degree-of-freedom device according to claim 1, wherein the grinding tool is attached via a member having a vibration absorbing function. 3. The multi-axis degree-of-freedom device according to claim 1, wherein the grinding tool is attached via an elastic body for controlling a pressing force. 4. The multi-axis degree-of-freedom device according to claim 1, wherein the grinding portion of the grinding tool is attached via a flexible joint. 5. The multiaxial degree-of-freedom device according to claim 1, wherein the grinding portion of the grinding tool is a cup type.