JPH11285910A - Inspection device for edge shape of drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inspect the shape of an edge of a drill by image processing automatically with high accuracy by using a sideward image taking camera in addition to an edge image taking camera, and focusing a pint of the edge image taking camera to the edge of the drill in a noncontact manner. SOLUTION: While a drill D supplied from a supply mechanism is held by an up-down mechanism 1, an edge of the drill D is image taken by an edge image taking camera 2 from above and the drill D is image taken by a sideward image taking camera 3 from a lateral direction. The mechanism 1 raises and lowers the drill D to adjust an end of the drill D to a focus position of the camera 2. The upward and downward movements of the drill D are controlled by a motor controller 5 to which an image processing result from the camera 3 is outputted, and the image taking result of the camera 3 is monitored by a drill D sideward image monitor 7. The camera 2 is connected to a host personal computer 4 via an image processor so that the shape of edge is determined good or not from the image obtained by taking the edge of the drill D.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for automatically detecting chipping or the like of a drill bit, and more particularly to an apparatus optimal for inspecting the shape of a small-diameter drill bit.

[0002]

2. Description of the Related Art As shown in FIG. 14A, a drill has a drill portion 51 having a twist groove at a tip of a shank 50, and a cutting blade 52 is provided at a tip of the drill portion 51. When the tip of the drill is viewed in the axial direction, the cutting edge is configured to be point-symmetrical about the chisel point P, as shown in FIG.
It has lips m ₁ and m ₂ that are substantially parallel to the trailing edge t, and an outer peripheral edge r that forms a margin by connecting the trailing edge t and the lips m ₁ and m ₂ .

[0003] As a technique for inspecting the cutting edge of such a drill, Japanese Patent Application Laid-Open Nos. 64-45502, 64-45503, and 1-1996 have been disclosed.
The thing described in 216752 is known. In this method, an image of the cutting edge is taken by a camera, and the obtained image is used as a binarized image, and a diagram of the cutting edge is obtained from an intersection and a bending point in the outer peripheral coordinates of the binarized image. Inspection is performed by obtaining data and comparing it with preset drill data. In addition, a shape inspection by the naked eye of an operator is also performed.

[0004]

However, the inspection technique based on the image processing described above has the following problems (1) to (3) particularly when inspecting a drill having a small diameter (0.5 mmφ or less). was there.

(1) It is difficult to focus the camera on the cutting edge, and it is difficult to perform a highly accurate inspection. In order to inspect the cutting edge shape of a small diameter drill by image processing, a camera combined with a high magnification lens is required. In general, a high-magnification lens has a shallow depth of field, so that it is not easy to align the cutting edge of the drill with the focus position of the lens. Therefore, it has been considered to align the cutting edge by contacting the bottom of the drill with the positioning block, or to align the cutting edge by contacting the cutting edge of the drill with the positioning block.

However, in the technique described above, there is a tolerance in the overall length of the drill, so that the height of the cutting edge varies. Further, in the technique described above, since the positioning block is brought into contact with the cutting edge of the drill, the cutting edge is easily broken or chipped.

(2) It is difficult to detect the rotation angle (direction) of the cutting edge. When inspecting the shape of the cutting edge by image processing, it is not possible to determine which direction the cutting edge is facing simply by imaging the cutting edge with a camera. Since the trailing edge of a small diameter drill is not longer than the cutting edge width compared to a drill with a large diameter (0.6 mmφ or more), it is not accurate to simply judge the longest line segment as the trailing edge. The rotation angle of the drill cannot be detected, and the result of the inspection of the cutting edge shape may be insufficient in accuracy.

For example, as shown in FIG. 15, when the direction of the trailing edge is erroneously detected by the angle θ, the correct cutting edge width is h, whereas the required cutting edge width h ′ is h / co.
sθ, and the size is different from the actual size.

(3) It is difficult to detect a lip corner (a corner formed by a lip and an outer peripheral edge) at a cutting edge. The outer peripheral edge of the drill bit is actually a curved line, but in the above-described technique, it is approximated to a straight line by image processing. Therefore, especially with a small diameter drill, the deviation between the curve and the straight line cannot be ignored, and the lip corner cannot be detected with high accuracy. As a result, defects such as chipping cannot be accurately determined.

For example, if the detection of the lip corner is correct, the chipping 60 of the cutting edge can be detected (FIG. 16A). However, when the outer periphery is approximated by a straight line, the outer periphery coordinates of the cutting edge are located outside the linear approximation model and the chipping is not performed. Overlook the detection of 60 (Figure 16B),
Conversely, it may be determined that a correctly shaped product is missing (FIG. 16C). Note that FIG.
, The half line indicates the straight-line approximation model, and the thin line indicates the outer peripheral coordinates of the cutting edge.

On the other hand, the inspection performed by the naked eye of the operator is not sufficient in terms of the variation in the inspection result by the operator and the working efficiency.

Accordingly, it is a main object of the present invention to provide an apparatus capable of automatically inspecting the shape of a cutting edge of a drill (especially a small diameter drill) with high accuracy by image processing.

[0013]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the first feature of the present invention is to use a lateral imaging camera separately from a cutting edge imaging camera, and to perform non-contact drilling. The configuration is such that the edge of the cutting edge imaging camera is focused on the cutting edge. That is, a device for inspecting the shape of the cutting edge based on an image of the cutting edge of the drill, a cutting edge imaging camera for imaging the tip of the drill from above, a ring-shaped illumination for illuminating the tip of the drill, and A side imaging camera for imaging, side illumination for projecting a drill to the side imaging camera, means for binarizing an image from each camera, and a drill from a binarized image obtained from the side imaging camera Means for calculating the deviation between the tip of the camera and the focus position of the cutting edge imaging camera, and a vertical mechanism for raising and lowering the drill based on the result of the calculating means and moving the tip of the drill to the focusing position of the cutting edge imaging camera. It is characterized by the following.

The second feature is that, when the tip of the drill is not taken into the field of view of the lateral imaging camera, the up / down mechanism is controlled to control the image by the lateral imaging camera until the tip of the drill enters this field of view. Capture, judge presence of drill tip,
It consists in repeating the lifting of the drill by the vertical mechanism. That is, when the position of the drill tip is lower than the field of view of the side imaging camera, the drill is moved upward, and when the position of the drill tip is high, the drill is moved downward, so that it is within the field of view of the side imaging camera. It is characterized in that control means for controlling the up-and-down mechanism so as to accommodate the tip of the drill is provided.

A third feature is that, after an image of a drill tip is obtained by the above-mentioned apparatus using a cutting edge imaging camera, binarization processing is performed, and then rotation of the cutting edge is performed using histogram creation and linear approximation together. Find the corner. That is, an image captured by aligning the tip of the drill with the focus position of the cutting edge imaging camera is converted into a binarized image by the binarization processing means, and the outer peripheral coordinates of the binarized image of the drill bit are obtained. Histograms of various directional components, find the angle of the maximum frequency,
A point group forming a trailing edge is extracted from the outer peripheral coordinates based on the angle, and the obtained point group is linearly approximated to detect a rotation angle of the cutting edge.

Further, a fourth feature is that an approximate model for accurately detecting a lip corner by grasping the outer peripheral edge portion of the drill bit as a curve and comparing it with the outer peripheral coordinates of a binarized image of the drill bit is provided. Is to form. That is, the outer peripheral coordinates of the drill bit are rotationally converted by the angle determined by the rotation angle detecting means, and the outer peripheral coordinates of the binarized image of the drill bit after the rotation conversion are linearly approximated to the coordinates other than the outer peripheral edge. Find a point equidistant from each lip on the perpendicular bisector of the trailing edge on the approximate straight line, and find a circle whose diameter is the length of the trailing edge with this point as the center point. It is characterized by comprising means for forming an approximate model from a straight line whose coordinates are approximated.

The inspection apparatus has a supply mechanism for sequentially supplying the drills to the inspection apparatus, and a sorting mechanism for storing the drills inspected by the inspection apparatus separately into non-defective products and defective products. From the supply of the drill to the inspection device to the sorting process after the inspection can be collectively and automatically processed.

[0018]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram showing a schematic configuration of an inspection apparatus, FIG. 2 is a block diagram showing an image pickup system in the inspection apparatus, and FIG. 3 shows a drill supply mechanism before inspection and a drill sorting mechanism after inspection in the apparatus of the present invention. FIG. 2 is an overall configuration diagram showing a mounted state.

As shown in FIG. 1, the inspection apparatus according to the present invention includes a vertical mechanism 1 for holding a drill D sent from a supply mechanism (described later), and a cutting edge imaging camera for imaging the cutting edge of the drill D from above. 2 and a lateral imaging camera 3 for imaging the drill D from the side, all of which are connected to a host personal computer 4 (computer).

The up-and-down mechanism 1 is a mechanism for raising and lowering the drill D, and performs an operation of adjusting the tip of the drill D to the focus position of the cutting edge imaging camera 2. For this purpose, a motor controller 5 is provided between the up-and-down mechanism 1 and the host personal computer 4, and commands the image processing result from the side imaging camera 3 to the motor controller 5 to control the ascent / descent operation of the drill D.
The side imaging camera 3 is connected to the host personal computer 4 via the image processing board 6, and displays the imaging result on a drill side image monitor 7.
It is configured to be able to monitor. The cutting edge imaging camera 2 is connected to the host personal computer 4 via the image processing device 8 so that the quality of the cutting edge shape can be determined from an image obtained by imaging the cutting edge of the drill D. 9 can be confirmed. Further, the totalization and display of the inspection results can be confirmed on the result display 10. Note that the host personal computer is also configured to link the respective transport systems in the pre-inspection drill supply mechanism and the post-inspection drill sorting mechanism described below.

FIG. 2 shows the configuration of the imaging system in the inspection apparatus having such a configuration. Drill vertical mechanism 1, from bottom to top
The ring-shaped illumination 11 and the cutting edge imaging camera 2 are coaxially arranged. The drill D is held by the vertical mechanism 1 with the tip facing upward, and the cutting edge imaging camera 2 captures an image of the cutting edge through the circular hole of the ring-shaped illumination 11. Since the ring-shaped illumination 11 illuminates the drill D from all around, an even image can be obtained. On the other hand, the side imaging camera 3 and the side illumination 12 are horizontally opposed to each other with the tip of the drill interposed therebetween, so that the projected image of the drill bit can be captured by the side imaging camera 3.
Further, the side imaging camera 3 is attached so that the cutting edge imaging camera 2 is focused on the position of a horizontal line that divides the field of view into two vertically. Each of the cameras 2 and 3 is optimally a CCD camera combined with a high-magnification lens.

In the inspection by this apparatus, the image of the side imaging camera 3 is processed, and the drill bit is moved to the focus position of the blade imaging camera 2. → The edge imaging camera 2 takes an image of the blade, and processes the image. Is performed by comparing the approximate model with the outer periphery coordinates of the blade edge image to determine the presence or absence of a shape defect. A schematic flowchart is shown in FIG.

First, the procedure for adjusting the cutting edge of the drill to the focus position of the cutting edge imaging camera will be described. When the drill is illuminated by the side illumination and the drill is imaged from the side by the side imaging camera, a projected image of the tip of the drill is obtained. This projected image is binarized to obtain a binarized image in which the drill bit 20 is displayed in black as shown in FIG.

In this binarized image, since the camera has a high magnification and a narrow field of view, no drill is shown when the cutting edge does not enter the field of view of the side camera (FIG. 6).
A) and the case where the root side of the drill is reflected but the cutting edge protrudes (FIG. 6B). In the former case, it is determined that no black pixel exists in the binary image, and a control signal is issued to move the drill upward. In the latter case, it is determined that there is a portion where black pixels continue from the lower end to the upper end in the Y (vertical) direction of the binarized image, and a control signal is issued to move the drill downward. Until the cutting edge of the drill is captured in the field of view of the lateral imaging camera, the capture of the image, the recognition and determination of the tip of the drill, and the elevation of the drill are repeated. Further, in order to detect the breakage of the drill and the total length defect, if the amount of vertical movement exceeds a certain threshold value (for example, the total length tolerance), it is determined to be defective.

If the cutting edge is in the field of view of the lateral imaging camera (FIG. 5A), the difference d between the vertex of the cutting edge 20 and the position of the horizontal line H that divides the field of view vertically into two, ie, the focus position of the cutting edge imaging camera.
Is calculated (FIG. 5B). Then, the drill is raised and lowered by the difference d obtained by the calculation, and the cutting edge is adjusted to the focus position of the cutting edge imaging camera (FIG. 5C).

Next, a procedure for capturing an image of the tip of the drill with the cutting edge imaging camera and creating an approximate model for shape inspection will be described. When the cutting edge is adjusted to the focus position of the cutting edge imaging camera, imaging is performed. As shown in FIG. 7, an image (hatched portion) in which the cutting edge portion is displayed in white reflection is obtained. This image is binarized to extract the outer peripheral coordinates of the cutting edge. The extracted outer periphery coordinates are substantially represented as shown in FIG.

However, at this stage, it is not known which direction the cutting blade is facing. Therefore, the direction of the cutting blade is determined by the following procedure. First, determine the frequency of the local direction (angle) components of the outer circumferential coordinates (see FIG. 8A) as a histogram (see FIG. 8B), and coarse direction theta ₁ of the angle trailing edge t of the maximum frequency (Fig. 8C reference).

Next, as shown in FIG. 9, the outer peripheral coordinates of the cutting edge are roughly rotated based on the angle θ ₁ . A group of training edge points is extracted from the coordinates of the outer circumference of the cutting edge in the extraction areas A1 and A2 based on the image subjected to the coarse rotation conversion. FIG. 10 shows a procedure for setting the extraction areas A1 and A2. FIG. 10 shows the outer peripheral coordinates of the cutting blade subjected to the coarse rotation conversion. The horizontal direction in FIG. 10 is the X direction, and the vertical direction is the Y direction.
It is shown as a direction. Here, in the outer peripheral coordinates of the cutting edge, the left end in the X direction in the X direction is Xmin, the right end is Xmax, and the width of both is a, Y
The upper end in the direction is Ymin, the lower end is Ymax, and the length between them is b.

Since the outer peripheral coordinates of the cutting edge are oriented so that the direction of the trailing edge is substantially aligned with the Y direction by the coarse rotation conversion, the trailing edge point group is represented by a straight line Xc = (Xmin +
Xmax) / 2. Therefore, in the X direction, the range of Xc-ha ≦ X ≦ Xc + ha (h is a constant) is defined as the width of the extraction areas A1 and A2. On the other hand, in the Y direction, the lengths of the extraction areas A1 and A2 are separately defined by the upper and lower cutting edges so as not to extract the point group of the chisel edge and the outer peripheral edge. Since the middle in the Y direction is represented by a straight line Yc = (Ymin + Ymax) / 2, the upper cutting edge is Ymin + (kb / 2) ≦ Y ≦ YC− (qb / 2),
For the lower cutting edge, the range of YC + (qb / 2) ≦ Y ≦ Ymax- (kb / 2) is set as the length of the extraction areas A1 and A2. Note that k and q are constants.

Next, the angle of a straight line obtained by linearly approximating the trailing edge point group extracted from each of the extraction areas A1 and A2 is determined. Here, the angle of the approximate straight line is determined by setting the Y direction of the image to 0 °. Then, the average angle (θ ₂ ) of the angles obtained from the extraction areas A 1 and A 2 is obtained, and θ ₁ + θ ₂ = θ
The original image (the image before coarse rotation conversion) is rotationally converted again by the angle θ obtained as described above, and the orientation is adjusted so that the trailing edge is along the vertical direction of the image.

Further, the outer peripheral coordinates after the rotation conversion (FIG. 1)
1A) is linearly approximated except for the outer peripheral portion (FIG. 11B).
That is, the trailing edge t, the two lips m ₁ and m _2, and the intersection line with the trailing edge connecting the two lips m ₁ and m ₂ are linearly approximated. Since the outer peripheral edge portion is a portion where the drill groove is not cut, a part of the outer peripheral circle of the drill remains as it is. Therefore, as shown in FIG.
Exists on the vertical bisector n of the approximate line t of the trailing edge. Further, the center of the outer circumferential circle is located at a position equidistant from both lips m ₁ and m _{2 due} to the manufacturing conditions of the drill.
Therefore, a circle having the center O at a point on the vertical bisector n and equidistant from both the lips m ₁ and m ₂ and having the diameter l of the trailing edge as the diameter may be set as the outer circumferential circle. Then, by matching this outer peripheral circle with the approximate curve excluding the outer peripheral edge,
As shown in FIG. 13, an approximate model of the cutting edge having a curved outer peripheral edge portion r is obtained, and the lip corner can be detected with high accuracy.

When an approximate model of the cutting edge is obtained, a defect such as a chip is detected by comparing the model with the outer peripheral coordinates (FIG. 11A) of the cutting edge and measuring the dimensions. That is,
If the deviation between the approximate model and the outer peripheral coordinates exceeds a predetermined range, it is determined that a chip has occurred. Further, a shape defect can be detected by obtaining a cutting edge width from the approximate model and comparing the cutting edge width with a predetermined cutting edge width stored in the host personal computer in advance. When calculating the cutting edge width, since the approximate model is obtained by accurately obtaining the rotation angle of the cutting edge, it is easy to obtain the accurate cutting edge width by obtaining the horizontal distance between the trailing edge and the lip in the image. Can be.

FIG. 3 shows a state in which a drill supply mechanism before inspection and a drill sorting mechanism after inspection are mounted on the inspection apparatus. The supply mechanism includes a case 30 for storing a pre-inspection drill, an XY table 31 for moving the case 30, and a drill transport system for extracting the drill D in the case and transporting the drill D to the inspection device. By operating the XY table 31, the drills are sequentially held by the transport system and transported to the rotating mechanism 32 attached to the inspection device.

On the other hand, the sorting mechanism includes a transport system for the drill after inspection, a case 40 and 41 for non-defective and defective drills,
An XY table 42 for moving both cases 40 and 41 is provided. Drills determined to be non-defective and non-defective by the inspection device are transported to each case 40 and 41 by the transport system, and
By the operation of the table 42, they are sorted into the good case 40 and the defective case 41, respectively. Since these supply mechanism and sorting mechanism are linked in accordance with the discrimination speed of the inspection apparatus, it is possible to collectively and automatically process from supplying a drill to the inspection apparatus to sorting good and defective products.

[0035]

As described above, according to the device of the present invention, the following effects can be obtained. (1) Since the drill bit can be adjusted to the focus position of the blade imaging camera in a non-contact manner, unlike the contact type alignment using the positioning block, the drill does not chip. In addition, since a sharp and focused image can be obtained with certainty, accurate shape inspection can be performed even with a drill having a particularly small diameter.

(2) The local directional component of the outer peripheral coordinate of the cutting edge in the binarized image is converted into a histogram to determine the angle of the maximum frequency, and a linear approximation of the outer peripheral coordinate is performed based on this angle to obtain the cutting edge. The rotation angle (direction of the trailing edge) can be accurately detected. Therefore, the measurement of the cutting edge width and the like can be performed more accurately, and a highly accurate shape inspection can be performed.

(3) By recognizing the outer peripheral edge of the cutting edge as a curve, a precise approximation model in which the lip corner is accurately detected can be obtained. Thereby, it is possible to prevent the shape defect of the drill from being overlooked and to conversely judge a non-defective product as a defective product.

(4) By linking the drill supply mechanism to the inspection device with the drill sorting mechanism after inspection, a series of operations from the supply of drills to inspection to the sorting of non-defective and defective products can be performed automatically. Can be done

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a device of the present invention.

FIG. 2 is a configuration diagram illustrating an imaging system in the apparatus of the present invention.

FIG. 3 is a configuration diagram showing a state in which a drill supply mechanism and a sorting mechanism after inspection are mounted on the apparatus of the present invention.

FIG. 4 is a flowchart of an inspection procedure in the method of the present invention.

5A and 5B show images of a side imaging camera, wherein FIG. 5A is an image diagram of a tip of a drill, FIG. 5B is an explanatory diagram of a difference d between a cutting edge and a horizontal line, and FIG. It is an image figure at the time.

FIG. 6A is an explanatory diagram in a case where a side imaging camera cannot take in a drill at all, and FIG. 6B is an explanatory diagram in a case where a root portion of a drill is taken in;

FIG. 7 is a schematic diagram of an image of a drill bit by a blade image capturing camera.

8A is a schematic diagram showing a local directional component in the outer peripheral coordinates of the cutting edge, FIG. 8B is a graph showing a histogram of the directional component, and FIG. It is.

FIG. 9 is an explanatory diagram when coarse rotation conversion is performed on the outer periphery coordinates of the cutting blade.

FIG. 10 is an explanatory diagram of an extraction area setting procedure.

FIG. 11 (A) is a schematic diagram showing the outer periphery coordinates of a cutting blade,
(B) is a linear diagram approximating a portion excluding the outer peripheral edge of the cutting blade.

FIG. 12 is an explanatory diagram showing the center of an outer peripheral circle that forms the outer peripheral edge of the cutting blade.

FIG. 13 is a schematic diagram showing a procedure when creating an approximate model of a cutting edge.

14A is a schematic side view of a drill, and FIG. 14B is a schematic view of a drill bit.

FIG. 15 is an explanatory diagram showing an error that occurs in the cutting edge width when the angle of the trailing edge is detected and made an error.

16A and 16B show a state in which a conventional straight-line approximation model is compared with the outer periphery coordinates of a cutting edge, wherein FIG. 16A is an explanatory diagram in which chipping can be normally detected, FIG. 16B is an explanatory diagram in which chipping cannot be detected, (C) is an explanatory diagram in a case where it is erroneously recognized that a normal cutting edge is missing.

[Description of Signs] 1 vertical mechanism 2 cutting edge imaging camera 3 side imaging camera 4 host personal computer 5 motor controller 6 image processing board 7 drill side image monitor 8 image processing device 9 cutting edge image monitor 10 result display display 11 ring-shaped illumination 12 Side illumination 20 Cutting edge 30 Case 31,42 XY table 32 Rotation mechanism
40 Good case 41 Defective case 50 Shank 51 Drill part 52
Cutting blade 60 chipped

Claims (5)

[Claims] An apparatus for inspecting the shape of a cutting edge based on an image of the cutting edge of the drill, comprising: a cutting edge imaging camera for imaging the tip of the drill from above; a ring-shaped illumination for illuminating the tip of the drill; A lateral imaging camera that captures images from the side, a lateral illumination that projects a drill onto the lateral imaging camera, a unit that binarizes images from each camera, and a binarization obtained from the lateral imaging camera Means for calculating the deviation between the tip of the drill and the focus position of the cutting edge imaging camera from the image, an up and down mechanism for raising and lowering the drill based on the result of the calculating means, and moving the tip of the drill to the focusing position of the cutting edge imaging camera; An inspection device for the shape of a cutting edge of a drill, comprising: 2. When the position of the drill tip is lower than the field of view of the lateral imaging camera, the drill is moved upward, and when the position of the drill tip is high, the drill is moved downward. 2. The inspection apparatus according to claim 1, further comprising control means for controlling a vertical mechanism so that the tip of the drill falls within the field of view. 3. An image taken by aligning the tip of the drill with the focus position of the cutting edge imaging camera is converted into a binarized image by a binarizing processing means, and outer peripheral coordinates of the binarized image of the drill bit are obtained. A histogram of the local directional components of, the angle of the maximum frequency is obtained, a point group forming a trailing edge is extracted from the outer peripheral coordinates based on this angle, the obtained point group is linearly approximated, and the 3. The apparatus for inspecting the shape of a cutting edge of a drill according to claim 2, further comprising means for detecting a rotation angle. 4. The outer peripheral coordinates of the drill bit are rotationally converted by the angle determined by the rotation angle detecting means, and the coordinates other than the outer peripheral edge of the outer peripheral coordinates of the binary image of the drill bit after the rotation conversion are linearly approximated. Then, find a point equidistant from each lip on the perpendicular bisector of the trailing edge on this approximate straight line, find a circle whose diameter is the length of the trailing edge with this point as the center point. 4. The apparatus for inspecting the shape of a drill bit according to claim 3, further comprising means for forming an approximate model from a straight line that approximates coordinates other than the part. 5. The apparatus according to claim 1, further comprising a supply mechanism for sequentially supplying drills to the inspection device, and a sorting mechanism for storing the drills inspected by the inspection device separately into non-defective products and defective products. Inspection device for drill tip shape.