JP2015136771A - Dressing device and method of rotary grind stone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dressing device and a dressing method of a rotary grind stone in which a removal amount (dressing amount) needed for dressing to the original processing surface shape can be accurately set with a same measurement method and without using an expensive instrument, and dressing can be implemented without removing the grind stone more than needed, even in a case that a processing surface of the rotary grind stone is partially concaved due to wearing.SOLUTION: (A) the wearing shape of a processing surface 1a of a rotary grind stone 1 is measured through following of the processing surface 1a by a measuring jig 22 under a condition that the processing surface 1a is pressed to the protruding part 22a of the measuring jig 22 with a constant pressing force, (B) the removal amount is set as needed for removing by dressing the processing surface 1a from the measured wearing shape of the processing surface 1a to the shape before wearing, and (C) the processing surface 1a of the rotary grind stone 1 is pressed to the dresser surface 24a of a dresser tool 24, to remove the removal amount from the outline surface of the processing surface 1a.

Description

  The present invention relates to a dressing apparatus and method for a rotating grindstone having a machining surface that is line-symmetric with respect to an axis.

  For example, in an industrial robot having six axes, a force sensor is provided at the base of the rotating grindstone, and machining (for example, deburring) is performed while following the shape of the workpiece. In such a robot, by controlling the pressing force during processing, it is possible to absorb deformation due to wear of the grindstone, an error in the installation position of the workpiece, and the like, and perform stable processing.

  However, with this deburring process, the grindstone gradually wears, and the processed surface changes to unevenness. Therefore, it is necessary to dress the processed surface of the grindstone.

  Conventionally, dressing of a grindstone in such a robot has been performed by processing, for example, a preset removal amount (dressing amount). This removal amount is set to be larger than the actual wear amount so as not to leave a correction in consideration of variations in the surface shape.

  In addition, for example, Patent Documents 1 to 3 are disclosed as dressing means for a grindstone.

Patent Literature 1 “Force Control Robot Grinding Wheel Compensation Method” corrects the grinding wheel center position (TCP) by pressing the grinding wheel against the reference surface before and after machining, calculating the amount of grinding wheel wear by comparing the contact position. To do.
The “automatic grinding apparatus” of Patent Document 2 captures the shape of the grindstone with a camera, compares the image of the grindstone photographed in advance with the photographed image, and determines whether the grindstone is worn or whether the grindstone is damaged. Further, the correction of the center position (TCP) of the grindstone accompanying the change in shape from the photographed image is also performed simultaneously.
The “grinding wheel dressing apparatus” of Patent Document 3 performs dressing until the driving voltage of the vibrator is detected simultaneously with the dressing and the magnitude of the fluctuation of the driving voltage becomes a predetermined value or less.

JP-A-7-205022 JP 2000-202771 A JP-A-8-66851

The conventional grinding stone dressing means described above has the following problems.
In the conventional general dressing means, the grindstone is cut more than necessary, so the life of the grindstone is shortened.
In the means of Patent Document 1, it is necessary to change the measurement method according to the wear form of the grindstone.
For example, in the case of C-chamfering using a cylindrical grindstone, the entire outer surface of the grindstone is not worn uniformly, but only the portions that are in contact during machining are partially recessed due to wear. In this case, an accurate wear amount cannot be measured only by pressing the outer surface of the cylindrical grindstone against the reference surface.
Since the means of Patent Document 2 requires a camera and an image processing device, the cost of the device itself increases.
Since the means of Patent Document 3 determines the completion of dressing based on the magnitude of fluctuation of the driving voltage of the vibrator, the actual removal amount (dressing amount) cannot be determined.

  The present invention has been developed to solve the above-described problems. That is, the object of the present invention is to eliminate the need for dressing up to the original processing surface shape even when the processing surface of the rotating grindstone is partially dented due to wear by the same measurement method without using expensive equipment. An object of the present invention is to provide a dressing apparatus and method for a rotating grindstone that can accurately set the amount (dressing amount) and perform dressing without removing the grindstone more than necessary.

According to the present invention, a rotating grindstone having a machining surface that is line-symmetric with respect to an axis,
A grindstone rotating motor that rotationally drives the rotating grindstone around the axis;
A force sensor for detecting an external force acting on the rotating grindstone;
A robot arm capable of moving the position and posture of the rotating grindstone in a three-dimensional space;
A robot controller for controlling the robot arm, and a dressing device for a rotating grindstone in a processing robot comprising:
A measuring jig having a protrusion capable of contacting the processed surface;
A dresser tool having a dresser surface in contact with the processing surface of the rotating grindstone;
A dressing control unit, the dressing control unit,
In a state where the processing surface is pressed against the protruding portion of the measuring jig with a constant pressing force, the processing surface is copied with the measuring jig, and a wear measuring unit that measures the wear shape of the processing surface;
A removal amount setting unit for setting a removal amount necessary to remove the work surface from the wear shape to a shape before wear by dressing; and
There is provided a dressing device for a rotating grindstone, comprising: a dressing unit that presses a processing surface of the rotating grindstone against a dresser surface of the dresser tool to remove the removal amount from the outer surface of the processing surface. The

Moreover, according to the present invention, a rotating grindstone having a machining surface line symmetrical with respect to the axis,
A grindstone rotating motor that rotationally drives the rotating grindstone around the axis;
A force sensor for detecting an external force acting on the rotating grindstone;
A robot arm capable of moving the position and posture of the rotating grindstone in a three-dimensional space;
A method for dressing a rotating grindstone in a processing robot provided with a robot controller for controlling the robot arm,
A measuring jig having a protrusion capable of contacting the processed surface;
Preparing a dresser tool having a dresser surface that can come into contact with the processing surface of the rotating grindstone,
(A) In a state where the processing surface is pressed against the protruding portion of the measuring jig with a constant pressing force, the processing surface is copied with the measuring jig, and the wear shape of the processing surface is measured.
(B) Set a removal amount necessary for removing the processed surface from the wear shape to the shape before wear by dressing;
(C) A rotating grindstone dressing method is provided, wherein the removal amount is removed from the outer surface of the processed surface by pressing the processed surface of the rotating grindstone against the dresser surface of the dresser tool.

In (A), the rotary grindstone is pressed in the radial direction while feeding the rotary grindstone in the axial direction, and the relationship between the displacement X in the feed direction and the displacement Y in the push direction is acquired.
In (B), the difference between the maximum displacement and the minimum displacement in the pressing direction in the relationship is set as the removal amount.

In (A), the rotary grindstone is pressed in the radial direction while feeding the rotary grindstone in the axial direction, and a plurality of data indicating the relationship between the displacement X in the feed direction and the displacement Y in the push direction is extracted.
In (B) above,
(B1) A Hough transform is performed on each of the data to convert it into measurement points on the ρ-θ coordinate,
(B2) A point group consisting of more measurement points than the set threshold value is selected from the point groups close to the measurement point,
(B3) A representative point cloud is selected from the selected point cloud,
(B4) A straight line on the XY coordinate corresponding to the representative point group is extracted as an outline representing the external surface of the rotating grindstone,
(B5) It is preferable that the maximum value of the distance between the data and the outline or a value obtained by adding a constant value to the maximum value is set as the removal amount.

  In (B3), it is preferable to select the point group having the largest number of measurement points constituting the point group as the representative point group.

  In (A), the pressing direction is set to one axis of the robot motion coordinate system.

In (A) above,
The pressing direction is calculated in advance, and the trajectory of the robot is transformed to derive the component of the pressing direction.

In (A) above,
(A1) Set a reference circle with a constant radius from the center of the circular measuring jig,
(A2) without rotating the rotating grindstone, its axis is positioned as a pressing start position on the reference circle, and a pressing distance from the pressing start position to the protruding portion of the measuring jig is measured,
(A3) The above (A2) is performed for a plurality of pressing start positions,
(A4) It is preferable to detect a position and direction having a chip larger than a threshold on the processed surface from a plurality of the pressing distances.

In (A), when a chip larger than a threshold is detected on the processed surface,
In (B), the removal amount by dressing of the processed surface excluding the portion having the chip is set to the minimum from the measured wear shape of the processed surface.

According to the apparatus and method of the present invention, the measuring jig having the protruding portion that can come into contact with the processing surface of the rotating grindstone is provided, and the processing surface of the rotating grindstone is pressed against the protruding portion of the measuring jig with a constant pressing force. In this state, the processing surface is copied with a measuring jig, and the wear shape of the processing surface is measured. Therefore, there is no need to change the measurement method according to the way the rotating grindstone is worn, and expensive equipment such as a camera or an image processing apparatus is not required.
Further, according to the present invention, since the processing surface of the rotating grindstone is copied by the protruding portion of the measuring jig, even when the processing surface of the rotating grindstone is partially recessed due to wear, dressing to the original processing surface shape is possible. The required removal amount (dressing amount) can be set accurately, and dressing can be performed without removing the grindstone more than necessary.

Therefore, the removal amount at the time of dressing can be minimized, the rotating grindstone can be used for a longer time, the grindstone replacement frequency can be reduced, and the grindstone cost can be suppressed.
Moreover, the completion of shaping can be confirmed by performing the same measurement after dressing.
Furthermore, the measuring jig only needs to have a protruding portion that can come into contact with the processing surface of the rotating grindstone, does not require a special device, and is a simple shape such as a rectangular parallelepiped block or a known shape such as a corner of a table. Is possible.

It is a system block diagram for enforcing the dressing method of the present invention. It is a whole flowchart of the dressing method of the rotary grindstone of the present invention. It is explanatory drawing of the measurement step of 1st Embodiment of this invention. It is explanatory drawing of the setting step of 1st Embodiment of this invention. It is a figure which shows 2nd Embodiment of this invention. It is explanatory drawing of Hough conversion. It is explanatory drawing of the straight line extraction by Hough transform. It is a relationship diagram of displacement in the pressing direction and displacement in the feed direction. It is explanatory drawing of the point group showing a straight line. It is explanatory drawing of removal amount setting. It is a figure which shows 3rd Embodiment of this invention. It is a figure which shows 4th Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

FIG. 1 is a system configuration diagram for carrying out the dressing method of the present invention.
In this figure, a processing robot 10 is a robot that includes a rotating grindstone 1 and performs processing such as deburring while following the shape of a workpiece (not shown).
The rotating grindstone 1 has a machining surface 1 a that is line-symmetric with respect to the axis Z. In this figure, the processing surface 1a is a cylindrical surface, but it may be conical, spherical, or other shapes. Further, the rotating grindstone 1 is not limited to a grindstone, and may be a carbide bar or the like.

  In this example, the processing robot 10 is an articulated robot, but the present invention is not limited to this, and may be another robot.

  In FIG. 1, the processing robot 10 includes a grinding wheel rotating motor 12, a force sensor 14, a robot arm 16, and a robot control device 18.

  The grindstone rotating motor 12 rotates the rotating grindstone 1 about the axis Z.

The force sensor 14 is, for example, a strain gauge, a load cell, or the like, and detects an external force acting on the rotating grindstone 1.
In this example, the force sensor 14 is a six-axis sensor capable of measuring a force (Fx, Fy, Fz) in three orthogonal directions and a torque (Tx, Ty, Tz) around each axis. The force sensor 14 is attached to a robot arm 16 that can move three-dimensionally, and has six degrees of freedom external force (forces Fx, Fy, Fz in three directions and torques Tx, Ty, Tz around three axes) acting on the robot arm 16. ) Is detected.
In addition, this invention is not limited to this, Other force sensors may be sufficient as long as the external force which acts on the rotary grindstone 1 can be detected.

The robot arm 16 is configured such that a grindstone rotating motor 12 and a force sensor 14 are attached to the hand, and the position and posture thereof can be moved in a three-dimensional space.
In this example, the robot arm 16 is a robot arm of an articulated robot, but the present invention is not limited to this and may be another robot arm.

  The robot controller 18 is a numerical controller, for example, which measures the value of the force sensor 14 and controls the robot arm 16 with six degrees of freedom (three-dimensional position and rotation about three axes) by a command signal. Yes. The robot control device 18 controls the robot arm 16 to sequentially execute a plurality of operations of the rotating grindstone 1.

  In FIG. 1, a dressing device 20 for a rotating grindstone 1 according to the present invention includes a measuring jig 22, a dresser tool 24, and a dressing control unit 26. The measuring jig 22 and the dresser tool 24 are fixed in advance at predetermined positions (in this example, on the fixed support base 25).

The measuring jig 22 has a protrusion 22a (in this example, a corner of a rectangular parallelepiped block) that can come into contact with the processing surface 1a of the rotating grindstone 1. The measuring jig 22 only needs to have a protrusion 22a that can come into contact with the processing surface 1a of the rotating grindstone 1, and does not require a special device, and has a simple shape such as a rectangular parallelepiped block or a known shape such as a corner of a table. I just need it.
The shape of the protruding portion 22a of the measuring jig 22 varies depending on the shape of the processing surface 1a of the rotating grindstone 1 and the measurement accuracy. For example, in order to measure an acute angle dent of the processed surface 1a, an edge having a smaller angle than the dent of the processed surface 1a is required on the protruding portion 22a.
The position of the protruding portion 22a is stored in the robot control device 18.

The dresser tool 24 has a dresser surface 24a that can come into contact with the processed surface 1a of the rotating grindstone 1, and presses and shapes the processed surface 1a of the rotated rotating grindstone 1. The dresser surface 24a is a flat surface in this example, but may have other shapes. The dresser tool 24 may be a general dresser device or a file.
The position of the dresser surface 24 a is stored in the robot control device 18.

The dressing control unit 26 includes a wear measurement unit 26 a, a removal amount setting unit 26 b, and a dressing unit 26 c, and controls the robot arm 16 together with the robot control device 18. The dressing control unit 26 may be integrated with the robot control device 18 or may be constituted by another computer (PC).
The wear measuring unit 26 a measures the wear shape of the processed surface 1 a by copying the processed surface 1 a with the measuring jig 22 while pressing the processed surface 1 a against the protrusion 22 a of the measuring jig 22 with a constant pressing force.
The removal amount setting unit 26b sets a removal amount D necessary to remove the processed surface 1a from the measured wear shape to the shape before wear by dressing.
The dressing part 26c presses the processing surface 1a of the rotary grindstone 1 against the dresser surface 24a of the dresser tool 24 to remove the removal amount D from the outer surface of the processing surface 1a.

FIG. 2 is an overall flowchart of the dressing method for the rotating grindstone 1 of the present invention.
The dressing method of the rotary grindstone 1 of the present invention prepares the processing robot 10 and the dressing device 20 described above, and executes each step (process) of S1 to S3.

In the measurement step S1, the processing surface 1a is copied by the measuring jig 22 while the processing surface 1a is pressed against the protrusion 22a of the measuring jig 22 with a constant pressing force, and the wear shape of the processing surface 1a is measured. The constant pressing force should be a small value as long as the machining surface 1a can be accurately followed by the measuring jig 22.
In the measurement step S1, it is preferable that the rotating grindstone 1 is pressed against the measuring jig 22 without being rotated, and the copying operation is performed with a constant pressing force. Further, the position of the hand of the processing robot 10 during the copying operation (the position and posture of the TCP from the reference coordinate system) is recorded.

In the setting step S2, a removal amount D necessary for removing the processed surface 1a from the measured worn shape of the processed surface 1a to the shape before the wear by dressing is set. The shape before wear means a cylindrical surface, conical shape, spherical shape, and other shapes before wear.
That is, after the copying operation in the measurement step S1, the dressing removal amount D is set based on the fluctuation range of the grindstone shape from the recorded displacement Y in the pressing direction of the rotating grindstone 1.

In the dressing step S3, the processing surface 1a of the rotary grindstone 1 is pressed against the dresser surface 24a of the dresser tool 24 to remove the removal amount D from the outer surface of the processing surface 1a.
The dressing step S3 preferably controls the position of the rotating grindstone 1 and presses the rotated rotating grindstone 1 to a position where a constant pressing force can be obtained.
The rotating grindstone 1 does not have to be rotated. Moreover, you may dress by pressing the rotary grindstone 1 not by position control but by force control.
By this position control or force control, the rotating grindstone 1 is pressed against the dresser tool 24 and removed to the removal amount D set in the setting step S2.

  In the dressing step S3, it is preferable to measure the reaction force even during the dressing and stop the dressing if the reaction force has an abnormal value.

  After dressing in the dressing step S3, the process returns to the measuring step S1, and the same shape measurement as before dressing is performed to check whether or not the dent of the rotating grindstone 1 has been eliminated. If the variation width of the shape is within a certain value, the dressing is completed.

  FIG. 3 is an explanatory diagram of the measurement step S1 of the first embodiment of the present invention, and FIG. 4 is an explanatory diagram of the setting step S2 of the first embodiment of the present invention.

In the method of the first embodiment, in the measurement step S1, as shown in FIGS. 3A and 3B, the rotary whetstone 1 is pressed in the radial direction while the rotary whetstone 1 is fed in the axial direction, and the displacement in the feed direction is changed. The relationship between X and displacement Y in the pressing direction is acquired.
3A shows a case where the wear is small, and FIG. 3B shows a case where the wear is large. Moreover, the displacement Y of the pressing direction expanded to the upper right of FIG. 3 (A) (B) is shown.

  The pressing direction of the rotating grindstone 1 in the measurement step S <b> 1 is preferably set to one axis (for example, the x axis) of the operation coordinate system of the processing robot 10. By this method, the displacement Y in the pressing direction can be easily obtained from a change in one axis of the motion coordinate system of the processing robot 10.

  Note that the pressing direction of the rotating grindstone 1 in the measurement step S1 may be calculated in advance, and the component of the pressing direction may be derived by performing coordinate conversion on the trajectory of the processing robot 10. By this method, the displacement Y in the pressing direction can be obtained by setting the pressing direction to an arbitrary direction without restricting the pressing direction to one axis of the operation coordinate system of the machining robot 10.

In the method of the first embodiment, in the setting step S2, as shown in FIG. 4, the difference D between the maximum displacement and the minimum displacement in the pressing direction in the relationship between the displacement X in the feeding direction and the displacement Y in the pressing direction is removed. Set as.
4A shows a feeding direction and a pressing direction in FIG. 3B. Further, (B) is a relationship diagram between the acquired displacement X in the feeding direction and displacement Y in the pressing direction.

FIG. 5 is a diagram showing a second embodiment of the present invention.
In the method of the second embodiment, in the measurement step S1, the rotating grindstone 1 is pressed in the radial direction while feeding the rotating grindstone 1 in the axial direction, and the displacement X in the feeding direction and the pressing direction shown in FIG. A plurality of data indicating the relationship with the displacement Y is extracted.

Next, in setting step S2, Hough transform is performed on each data to convert it into measurement points on the ρ-θ coordinate. FIG. 5B shows the measurement points on the ρ-θ coordinate after conversion.
Next, a point group 2 consisting of more measurement points than the set threshold is selected from the point group 2 close to the measurement point in FIG. 5B, and a representative representative point group 3 is selected from the selected point group 2. .
Next, a straight line on the XY coordinates corresponding to the representative point group 3 is extracted as an outline 4 representing the outline of the rotating grindstone 1, and the maximum value of the distance between the data and the outline 4, or a constant value thereof. Is set to the removal amount D. The constant value is set in advance based on data variation.

  The representative representative point group 3 is selected, for example, by selecting the point group having the largest number of measurement points constituting the point group 2.

  According to the method of the second embodiment described above, even when there is a problem with the calibration error of the rotating grindstone 1, the influence can be reduced.

Hereinafter, straight line extraction by Hough transform will be described.
Assuming that a perpendicular line is drawn from the origin to a straight line y = ax + b in the coordinate system as shown in FIG. 6, the length of the perpendicular line is ρ, and the angle formed with the x axis is θ, ρ can be expressed by the following equation (1).
ρ = x cos θ + ysin θ (1)
From this, in the polar coordinate system, if one point (ρ, θ) is known, one straight line can be known.
This point (ρ, θ) is referred to as “Hough transform” where y = ax + b.

A group of straight lines passing through the point (x ₀ , y ₀ ) on the xy coordinate can be expressed by the following equation (2).
ρ = x ₀ cos θ + y ₀ sin θ (2)

When the points on XY, P1 (x ₁ , y ₁ ), P2 (x ₂ , y ₂ ), and P3 (x ₃ , y ₃ ) are represented on the ρ-θ coordinate according to the equation ( ₂ ), FIG. It becomes like this.
At this time, when the trajectories of the straight line groups passing through each point intersect at the same point, the three points are located on the same straight line, and a straight line passing through the three points can be obtained.

From equation (1), the calculation for deriving the straight line y = ax + b from (ρ, θ) is as follows.
a = −cos θ / sin θ = cot θ (3)
b = ρ / sin θ (4)
The process of deriving (a, b) from this (ρ, θ) is called “inverse Hough transform”.

In the second embodiment of the present invention, the displacement Y in the pressing direction and the feed as shown in FIG. 8 are obtained from the trajectory data of the hand of the processing robot 10 during the measurement operation recorded by the robot controller 18 using the Hough transform described above. A plurality of data of the direction displacement X (indicated by rectangles in the figure) are extracted.
Next, the above-mentioned Hough transform is performed on the displacement Y in the pressing direction and the displacement X in the feed direction to convert them onto the ρ-θ coordinates. A straight line (ρ, θ) passing through a larger number of points than the set threshold is selected from the trajectory of the straight line group passing through each converted point. The selected result is a point group 2 as shown in FIG.

There are a plurality of points in the vicinity of a certain straight line where the number of points located on the same straight line is equal to or greater than the threshold. Therefore, a straight line (ρ, θ) corresponding to the representative point group 3 is selected from the plurality of point groups 2.
The representative point group 3 is selected by, for example, classifying the point group 2 representing each straight line by a labeling process, regarding each as a connected component on a two-dimensional plane, and the center of gravity of the connected component as the peak of the point representing this straight line. The representative point group 3 is selected.
Note that a straight line having the largest number of points located on the same straight line may be simply used as the representative point group 3.

  As shown in FIG. 10, a straight line (outline 4) representing the machining surface 1a (outside surface) of the rotary grindstone 1 is extracted by the above-described processing, and the distance between each measurement point and the outline 4 representing the machining surface 1a Is the depth of the dent, and a value corresponding to the depth of the dent or a value obtained by adding a value corresponding to half of the variation of the measured value to the value is set as the dressing removal amount D.

FIG. 11 is a diagram showing a third embodiment of the present invention.
In the third embodiment, a circular disk is used as the measurement jig 22. In this case, the protrusion 22a of the measuring jig 22 is the outer peripheral surface of the disk. A reference circle 4 having a constant radius R is set in advance from the center of the measuring jig 22 (the center of the disk).
In the measurement step S1, first, as shown in (A), the axis Z is positioned as a pressing start position at an arbitrary position on the reference circle without rotating the rotating grindstone 1, and the measuring jig 22 is measured from the pressing start position. The pressing distance X1 to the protruding portion 22a is measured.
Next, this measurement is performed for a plurality of pressing start positions, and the pressing distances X2 and X3 are measured.
Next, as shown in (B), from the measured pressing distances X1, X2, and X3, the radius R1 of the machining surface 1a of the rotating grindstone 1 and the position and direction where the machining surface 1a has a chip 1b larger than a predetermined threshold value. Is detected.

That is, in the third embodiment, without rotating the rotating grindstone 1, the rotating grindstone 1 is pressed to follow the disc-shaped measuring jig 22 from a plurality of directions, and the trajectory of the hand of the processing robot 10 is recorded. From the recorded displacement Y in the pressing direction of the track, the outer diameter of the rotating grindstone 1 is measured, and the position and direction in which the chipped surface 1a of the rotating grindstone 1 has a chip 1b larger than a predetermined threshold is detected.
By this method, when there is a chip 1b larger than a predetermined threshold on the processed surface 1a, the position and direction can be detected.

FIG. 12 is a diagram showing a fourth embodiment of the present invention.
In the fourth embodiment, when a chip 1b (or a dent) larger than a predetermined threshold is detected on the processed surface 1a, if the processed surface 1a is dressed until the chip 1b disappears, the life of the rotating grindstone 1 becomes too short. Assume the case.
Therefore, in the fourth embodiment, when a chip 1b larger than a predetermined threshold is detected on the processed surface 1a, the portion with the chip 1b is not set as a dressing target, and the chipped shape is determined based on the measured wear shape of the processed surface 1a. The removal amount D by dressing of the processed surface 1a excluding a portion with 1b is set to the minimum.
By this method, as shown in (A), the shape of the rotating grindstone 1 is measured by the method of the third embodiment, and a portion where the outer surface of the rotating grindstone 1 has no chip 1b or unevenness is detected. Next, the workpiece is machined by correcting the position of the TCP so that the chipped portion 1b and the portion having no unevenness (used portion 1c) as shown in FIG. If the use location 1c is worn by the work of the workpiece, a portion having no chip 1b or unevenness can be similarly searched for and used as a new use location 1c.
In addition, when the entire surface of the rotating grindstone 1 is worn and a portion having no chip 1b or unevenness cannot be detected, dressing is performed by the above method.

According to the apparatus and method of the present invention described above, the measuring jig 22 having the protruding portion 22a that can come into contact with the processing surface 1a of the rotating grindstone 1 is provided, and the processing surface 1a of the rotating grindstone 1 is used as the protruding portion of the measuring jig 22. In a state where it is pressed against 22a with a constant pressing force, the machining surface 1a is copied by the measuring jig 22, and the wear shape of the machining surface 1a is measured. Therefore, it is not necessary to change the measurement method according to the way the rotating grindstone 1 is worn, and expensive equipment such as a camera or an image processing device is not required.
In addition, according to the present invention, since the processing surface 1a of the rotating grindstone 1 is imitated by the protruding portion 22a of the measuring jig 22, the original processing surface even when the processing surface 1a of the rotating grindstone 1 is partially recessed due to wear. The removal amount D (dressing amount) necessary for dressing up to the shape can be set accurately, and dressing can be performed without removing the grindstone more than necessary.

Accordingly, the removal amount D at the time of dressing can be minimized, the rotating grindstone 1 can be used for a longer time, the grindstone replacement frequency can be reduced, and the grindstone cost can be suppressed.
Moreover, the completion of shaping can be confirmed by performing the same measurement after dressing.
Furthermore, the measuring jig 22 only needs to have a protrusion 22a that can come into contact with the processing surface 1a of the rotating grindstone 1, and does not require a special device, and is known as a simple shape such as a rectangular parallelepiped block or a corner of a table. Any shape is possible.

  In addition, this invention is not limited to embodiment mentioned above, is shown by description of a claim, and also includes all the changes within the meaning and range equivalent to description of a claim.

D removal amount (dressing amount), displacement in X feed direction,
Y displacement in the pressing direction, Z axis, 1 rotating grindstone, 1a machined surface,
1b chipping (dent), 1c used place, 2 point group, 3 representative point group,
4 reference circle, 10 processing robot, 12 grinding wheel rotation motor,
14 force sensor, 16 robot arm, 18 robot controller,
20 dressing device, 22 measuring jig, 22a protrusion,
24 dresser tool, 24a dresser surface, 25 fixed support base,
26 dressing control unit, 26a wear measurement unit,
26b removal amount setting unit, 26c dressing unit

Claims (9)

A rotating whetstone having a machining surface line symmetrical with respect to the axis;
A grindstone rotating motor that rotationally drives the rotating grindstone around the axis;
A force sensor for detecting an external force acting on the rotating grindstone;
A robot arm capable of moving the position and posture of the rotating grindstone in a three-dimensional space;
A robot controller for controlling the robot arm, and a dressing device for a rotating grindstone in a processing robot comprising:
A measuring jig having a protrusion capable of contacting the processed surface;
A dresser tool having a dresser surface in contact with the processing surface of the rotating grindstone;
A dressing control unit, the dressing control unit,
In a state where the processing surface is pressed against the protruding portion of the measuring jig with a constant pressing force, the processing surface is copied with the measuring jig, and a wear measuring unit that measures the wear shape of the processing surface;
A removal amount setting unit for setting a removal amount necessary to remove the work surface from the wear shape to a shape before wear by dressing; and
A dressing device for a rotating grindstone, comprising: a dressing unit that presses a processing surface of the rotating grindstone against a dresser surface of the dresser tool to remove the removal amount from an outer surface of the processing surface. A rotating whetstone having a machining surface line symmetrical with respect to the axis;
A grindstone rotating motor that rotationally drives the rotating grindstone around the axis;
A force sensor for detecting an external force acting on the rotating grindstone;
A robot arm capable of moving the position and posture of the rotating grindstone in a three-dimensional space;
A method for dressing a rotating grindstone in a processing robot provided with a robot controller for controlling the robot arm,
A measuring jig having a protrusion capable of contacting the processed surface;
Preparing a dresser tool having a dresser surface that can come into contact with the processing surface of the rotating grindstone,
(A) In a state where the processing surface is pressed against the protruding portion of the measuring jig with a constant pressing force, the processing surface is copied with the measuring jig, and the wear shape of the processing surface is measured.
(B) Set a removal amount necessary for removing the processed surface from the wear shape to the shape before wear by dressing;
(C) A dressing method for a rotating grindstone, wherein the removal amount is removed from the outer surface of the processed surface by pressing the processed surface of the rotating grindstone against the dresser surface of the dresser tool. In (A), the rotary grindstone is pressed in the radial direction while feeding the rotary grindstone in the axial direction, and the relationship between the displacement X in the feed direction and the displacement Y in the push direction is acquired.
3. The dressing method for a rotating grindstone according to claim 2, wherein in (B), a difference between a maximum displacement and a minimum displacement in the pressing direction in the relationship is set as the removal amount. In (A), the rotary grindstone is pressed in the radial direction while feeding the rotary grindstone in the axial direction, and a plurality of data indicating the relationship between the displacement X in the feed direction and the displacement Y in the push direction is extracted.
In (B) above,
(B1) A Hough transform is performed on each of the data to convert it into measurement points on the ρ-θ coordinate,
(B2) A point group consisting of more measurement points than the set threshold value is selected from the point groups close to the measurement point,
(B3) A representative point cloud is selected from the selected point cloud,
(B4) A straight line on the XY coordinate corresponding to the representative point group is extracted as an outline representing the external surface of the rotating grindstone,
(B5) The dressing method for a rotating grindstone according to claim 2, wherein a maximum value of a distance between the data and the outline or a value obtained by adding a constant value to the maximum value is set as the removal amount.   5. The dressing method for a rotating grindstone according to claim 4, wherein in (B3), a point group having the largest number of measurement points constituting the point group is selected as a representative point group.   3. The dressing method for a rotating grindstone according to claim 2, wherein, in (A), the pressing direction is set to one axis of the motion coordinate system of the robot. In (A) above,
The method of dressing a rotating grindstone according to claim 2, wherein the pressing direction is calculated in advance, and the component of the pressing direction is derived by performing coordinate conversion on the trajectory of the robot. In (A) above,
(A1) Set a reference circle with a constant radius from the center of the circular measuring jig,
(A2) without rotating the rotating grindstone, its axis is positioned as a pressing start position on the reference circle, and a pressing distance from the pressing start position to the protruding portion of the measuring jig is measured,
(A3) The above (A2) is performed for a plurality of pressing start positions,
(A4) The dressing method for a rotating grindstone according to claim 2, wherein a position and a direction with a chip larger than a threshold value are detected from a plurality of the pressing distances. In (A), when a chip larger than a threshold is detected on the processed surface,
The rotating grindstone according to claim 8, wherein, in (B), the removal amount by dressing of the processed surface excluding the portion having the chip is set to a minimum from the measured wear shape of the processed surface. Dressing method.

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