JP2000190185A - Drill tip grinding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make high precision processing of a drill tip upon locating it precisely without being influenced by dispersion of the drill length and without making troublesome shape registration despite varying sort of drill. SOLUTION: A drill 8 is held by a drill holding mechanism 11 having a drill rotating mechanism, and the side face of the drill is photographed by a camera 13, and the obtained image is subjected to a processing so as to sense the position of the cutting groove edge, and the drill is rotated so that the sensed edge moves to the optimum point and located, and then the tip grinding is performed surface by surface using a grinding device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drill tip grinding machine capable of automatically positioning a drill tip for high precision.

[0002]

2. Description of the Related Art It is necessary to precisely position a drill when grinding the tip of a drill. For this purpose, a drill grinding apparatus is provided with a positioning mechanism.

A conventional example of the positioning mechanism is disclosed in, for example, Japanese Patent Application Laid-Open No. 63-114857. The mechanism disclosed in Japanese Patent Application Laid-Open No. 63-114857, which mechanically abuts the tip of a drill on a backing plate, performs positioning. It is not suitable for drills requiring positioning accuracy of 1 μm or less. 0.1mm diameter
A micro drill of about 1.3 mm requires extremely high positioning accuracy during grinding (a deviation of the rotation angle is about ± 0.5 degrees). The required accuracy is an error of about ± 0.44 μm with respect to the circumference in the case of a drill having a diameter of 0.1 mm, and it is difficult for the mechanism disclosed in the above publication to always maintain such accuracy.

For this reason, the positioning of the microdrill has been manually performed by an operator by enlarging the tip with a microscope, but this is inefficient and lacks certainty.

Accordingly, Japanese Utility Model Laid-Open No. 61-159151 discloses
The shape detector detects the shape of the drill tip, compares it with a pre-stored reference shape, determines the initial grinding position of the drill tip using an image pattern recognition device, and turns the spindle rotating device that holds the drill. We have proposed an automatic drill tip processing machine that controls the drill tip to move to the index point.

[0006]

Problems to be Solved by the Invention
Since the processing machine disclosed in Japanese Patent Publication No. 51 calculates the error amount of the drill tip shape with respect to the reference shape and corrects the deviation of the drill direction, the above error amount can be kept within an allowable value. If there is variation, accurate grinding cannot be performed even if positioning is performed. If the drill length is longer than the reference length, the amount of grinding at the tip becomes excessive, and if it is shorter than the reference length, the amount of grinding becomes insufficient. Conversely, the taper as shown in FIG. A processing defect called "taita" occurs,
The performance of the drill is not satisfactory.

[0007] Further, since relative positioning such as comparison with a reference shape is performed, labor for memorizing the reference shape of the drill tip for each product type and precise positioning at the time of inputting the reference shape are also required. There is also a problem.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a tip grinding machine which is not affected by variations in drill length, and which can precisely position a drill of a different type without registering a shape for each type to perform high-precision machining. Is an issue.

[0009]

In order to solve the above-mentioned problems, in the present invention, the position of the drill is determined by detecting the edge of the groove on the side surface of the drill and moving the edge to a predetermined position. As a specific device configuration therefor, a drill holding mechanism having a drill rotation mechanism, a camera for capturing an image of the side of the drill held by the holding mechanism, an image input device for inputting an image from the camera, and an arithmetic control for performing image processing Device and a grinding device for grinding the flank of the tip of the drill, wherein the arithmetic and control unit processes the input image to detect the position of the blade groove edge on the side surface of the drill, and the rotation mechanism is instructed by the arithmetic and control unit. However, the drill is rotated to a position where the detected blade edge reaches the target point.

In this drill tip grinding machine, an image of a side face of the drill is taken by a camera while rotating the drill with a holding mechanism, and the obtained image is processed by an arithmetic and control unit to recognize the edge of the groove. It is better to rotate the drill again so that it is within the field of view of the camera so that the position of the edge of the groove is detected and the drill is rotated to the positioning point. More preferably, the arithmetic and control unit detects a plurality of edges, selects a correct blade groove edge from the plurality of edges, and detects the position of the blade groove edge.

Further, the shape of the blade groove shape of the drill is formed into a formula, and the data of the blade groove edge position obtained by performing image processing on the formula stored in the arithmetic and control unit in advance is calculated to calculate the optimum grinding position of the drill tip. It is also preferable that the drill is positioned based on the calculation result.

[0012]

According to the present invention, since the positioning of the drill is performed with reference to the edge of the groove on the side surface of the drill, there is no influence from the variation in the drill length. The position where the grindstone is actually cut, not the end face of the drill, is accurately positioned at the grinding point, and high grinding accuracy is obtained.

Further, since the shape of the blade groove edge is the same regardless of the type of drill, it is not necessary to register the shape for each type.

[0014]

FIG. 1 shows a micro drill.
In the drawing, 1 is a cutting edge (lip), 2 is a margin portion, 3 is a blade groove (flute), 4 is a land, 5 is a blade groove edge, 6 is a flank, and 7 is a heel. The tip grinding machine of the present invention is particularly suitable for the micro drill, but also exhibits excellent effects when applied to grinding of other drills.

FIGS. 3 and 4 show an embodiment of a drill tip grinding machine according to the present invention. The grinding machine 10 includes a drill holding mechanism 11 shown in FIG. 3, a grinding device 12 having rotating whetstones 12a and 12b, a camera 13 shown in FIG.
4. An arithmetic and control unit 15 that processes the input image and controls the holding mechanism 11 and the grinding device 12.

Reference numeral 16 in FIG. 3 denotes a chuck which supplies the drill 8 to the holding mechanism 11 and removes the drill after the grinding is completed from the holding mechanism 11 and moves it to the carry-out point. Insert the drill 8. The holding mechanism 11 holds the inserted drill 8 and rotates from the position I to the position II, then further rotates to the position III and returns to the position I after grinding is completed. The holding mechanism 11 has a built-in drill rotation mechanism for rotating the held drill 8 together with the holder 11a.

The grinding device 12 is advanced and retracted in the direction of the arrow in FIG. 3 so as to match the tip angle of the drill 8, and the grinding wheel 12a grinds the second flank of the drill tip and the grindstone 12b grinds the third flank. . The grindstones 12a and 12b are inclined according to the inclination of the surface to be machined.

The camera 13 shown in FIG. 4 is provided at the position II shown in FIG. 3, where the drill 8 is positioned. The camera 13 captures an image of the side surface of the drill 8 through the lens 13a, and the image is taken into the arithmetic and control unit 15 through the image input device 14. The arithmetic and control unit 15 processes the captured image to recognize the blade groove edge 5, calculates the grinding position from the position of the blade groove edge 5, and completes the positioning by rotating the drill rotating mechanism based on the grinding position. I do. After this,
The holding mechanism 11 is rotated to the position III in FIG.
2a, 12b are cut into the tip of the drill while moving left and right (in the direction of the arrow in FIG. 3), and one side is ground. Also,
When the processing on one side is completed, the drill rotating mechanism rotates the drill 8 by 180 °, and the other side is ground by the grindstone to finish the grinding.

FIG. 5 shows a detailed flowchart of the positioning logic. FIG. 6 is an image taken by the camera 13 (a figure transcribed based on a photograph), and is a blade groove edge (an edge serving as a cutting edge) recognized in FIG. First, camera 1
The image of the side surface of the drill 8 is taken by 3 and the image (FIG. 6) is differentiated to the right to detect a point at which the brightness sharply increases in the right direction, that is, the edge 5. Assuming that the edge position on the image is xi (FIG. 7), the phase θi of this edge 5 is represented by the following equation (1): θi = n · θ + xi · θ ₀ / xOn: the number of times the drill is rotated at a fixed angle θ ₀ : angle in the x direction of the visual field xO: number of pixels in the x direction of the visual field

Next, the above processing is performed by rotating the drill 8 by θ degrees, and this operation is repeated until the drill rotates 360 ° to detect an edge and calculate an edge phase for the entire circumference of the drill. When aiming for high-precision positioning, it is necessary to increase the resolution of image processing, and the field of view of the camera is inevitably narrowed, so that only a part of the outer periphery of the drill does not enter the groove edge in the field of view Although a situation may occur, if the image processing is repeated by rotating the drill, the problem does not occur, and the edge of the blade groove can be reliably recognized.

Further, preferably, the drill is rotated by 360 ° to detect a plurality of edges. This can prevent erroneous recognition of the blade groove edge. For example, if two or more edges are detected as shown in FIG. 8 due to the attachment of dust or oil, the portions a and b having a wider interval than the others can be considered as the blade grooves 3. Either of the edges c and d in the clockwise direction with respect to the portions a and b) can be recognized as the correct blade groove edge 5. FIG.
Thus, even when the detection of one of the blade edges fails, the edge e at the clockwise position of the portion g where the phase interval is narrow among the edges e and f close to the blade groove 3 is the blade groove edge. Erroneous recognition of the edge does not occur.

Here, it is assumed that dust and oil adhering to the blade groove 3 in FIG. 1 are not detected. Lens 13a
Is focused on the edge serving as the cutting edge, so that the portion of the blade groove 3 is out of focus (FIG. 6), where the change in brightness is small and dust and oil are not detected as edges. Therefore, edge recognition by the above method is possible.

Since the blade groove edge 5 can be recognized and its phase can be measured in the above manner, the drill 8 is moved so that the recognized blade groove edge 5 enters the field of view of the camera 13 again for precise positioning.
Is rotated to image the side surface. Next, a binarization process is performed on the obtained image, and the coordinates of the detected blade groove edge 5 are measured as shown in FIG. Then, the edge coordinates are approximated by a straight line, and the drill 8 is rotated so that the straight line h passes through the center i of the image (centers on the center of the visual field of the camera).
Also, when actually grinding, there is a phase difference due to the twist of the drill from the center of the camera's field of view to the grinding point (grinding wheel position), so the drill is moved toward the final positioning target point with the phase difference added. Rotate further.

The phase difference of the blade groove due to the twist from the center of the visual field of the camera to the grinding point can be obtained by the following equation.

Now, in FIG. 11, a grinding wheel (12 in FIG. 3)
No. 2 flank to be processed by a) (hatched portion in the end view in FIG. 11)
Passes through x = 0, y = 0, Z = Zs = 0, and has a tip angle α,
Assuming the second clearance angle β, [Equation 2] −cos (α / 2) x + tanβ · y + sin (α /
2) It is represented as Z = 0. This means that the tip angle plane passing through AB, that is, −cos (α / 2) x + sin (α / 2) Z = 0,
.About.B and rotated by .beta.

Here, the drill 8 is located at the position of Z = Z ₁ .

[0027]

(Equation 1)

In this case, the optimum rotational position is obtained (state of the side surface in FIG. 11). At this time, the blade groove edge 5 is at the point C on x = 0.

On the other hand, assuming that the point 0 in FIG. 11 is the center of the field of view of the camera, before the above-mentioned optimum rotational position, that is, in FIG. 10, the straight line h (blade groove edge) is moved on the image center i. The blade groove edge 5 is at point O.

For this reason, the angle drill 8 corresponding to the amount of torsion during the time from (Z _{4 to} Z ₀ ) is rotated to rotate the blade edge 5
Is moved to the point C, the formula 3 is established and the drill is positioned at the optimum position.

The drill rotation angle at this time is expressed by the following equation (4): {(Z ₄ −Z ₀ ) / K} · 2π K: Twist pitch of the blade groove Z ₄ = Z ₁ + (π / 2 + tan ⁻¹ y ₁ / x ₁ ) × K / 2
π Z ₁ = − {cos (α / 2) × ₁ + tanβ × y ₁ }
/ Sin (α / 2) When this is arranged, the phase difference of the blade edge between the center of the visual field of the camera and the grinding point can be calculated by the following equation.

[0032]

(Equation 2)

The position where the blade groove edge 5 moves to the center of the visual field of the camera and is further rotated by the phase difference determined by the above equation is the final positioning target point. When the drill is rotated to position the blade groove edge there, The drill tip is accurately positioned at the grinding point. Although the edge of the blade groove may be out of the field of view of the camera when moving from the center of the field of view of the camera toward the final positioning target point, when the final positioning target point is calculated using the mathematical formula as described above, the edge becomes Accurate positioning can be performed even if it deviates from the field of view of the camera.

By this method of positioning, a positioning accuracy of ± 0.39 μm was actually realized by the prototype.

If the drill diameter is known, for example, the drill rotation angle required to move the straight line h in FIG. 10 to the image center i can be obtained. It is also possible to determine the final target positioning point from the phase difference of the edge up to the grinding point and rotate the drill so that the blade edge is positioned directly there,
Such an operation may be performed.

[0036]

As described above, in the present invention, the edge of the drill groove is detected, and the edge of the drill is moved to the optimum point to determine the position of the drill tip. Micro drills that require no positioning and require high positioning accuracy can satisfy the required accuracy and perform efficient tip grinding.

Further, since the positioning is performed by directly recognizing the blade groove edge, there is no need to register the shape for each product type, which is advantageous in terms of the production of a grinding machine.

In the case where the side surface is imaged over a wide area by rotating the drill, the recognition of the edge of the blade groove does not occur. In addition, the drill is rotated 360 ° and the correct blade groove is selected from the edges detected at several places. The one that selectively recognizes the edge does not cause erroneous grinding due to the misrecognition of the blade groove edge, and the one that formulates the drill blade groove shape and calculates the final positioning target point using the mathematical formula Even if the field of view is narrow, accurate positioning can be stably performed, and the performance and reliability of the grinding machine are further improved.

[Brief description of the drawings]

FIG. 1 (a) Side view of a micro drill (b) Front view of the same drill

FIG. 2 is a front view of a drill having a processing defect.

FIG. 3 is a diagram showing an embodiment of a tip grinding machine according to the present invention.

FIG. 4 is a diagram showing a camera, an image input device, and an arithmetic and control unit included in the grinding machine of FIG. 3;

FIG. 5 is a flowchart of positioning logic.

FIG. 6 is an image of a drill side taken by a camera.

FIG. 7 is a diagram showing edge positions on an image after processing;

FIG. 8 is an explanatory diagram showing an example of an edge detection point.

FIG. 9 is an explanatory diagram showing another example of an edge detection point.

FIG. 10 is a diagram showing a straight line connecting edge coordinates;

FIG. 11 is an explanatory diagram for a mathematical expression for calculating a final positioning target point.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cutting edge 2 Margin part 3 Blade groove 4 Land 5 Blade groove edge 6 Flank face 7 Heel 8 Drill 10 Drill tip grinding machine 11 Drill holding mechanism 11a Holder 12 Grinding device 12a, 12b Rotating grindstone 13 Camera 13a Lens 14 Image input device 15 Arithmetic controller 16 Chuck

Continued on the front page. (72) Inventor Tokua Hamada 1-1-1, Kunyo-Kita, Itami City, Itami Works, Sumitomo Electric Industries, Ltd. Sumiden Precision Co., Ltd.

Claims (4)

[Claims] 1. A holding mechanism for a drill having a drill rotating mechanism, a camera for capturing an image of a side surface of the drill held by the holding mechanism, an image input device for inputting an image from the camera, an arithmetic control device for performing image processing, and a drill The arithmetic and control unit processes the input image to detect the position of the blade edge on the side surface of the drill, and the rotation mechanism detects the position of the blade groove edge on the drill side by a command from the arithmetic and control unit. A drill tip grinding machine characterized in that the drill is rotated to a position where the set blade groove edge reaches a target point to position the drill tip at a grinding point. 2. An image of a side surface of a drill is taken by a camera while rotating the drill by a holding mechanism, and the obtained image is processed by an arithmetic and control unit to recognize a blade groove edge. 2. The drill tip grinding machine according to claim 1, wherein the drill is rotated again to a position where the drill enters, and the position of the blade groove edge is detected and the drill is rotated to the positioning point. 3. The rotation of the drill when imaging the side surface of the drill is 360.
3. The drill tip grinding machine according to claim 2, wherein the arithmetic and control unit detects a plurality of edges, and selects a correct blade groove edge from among them to detect the position of the blade groove edge. 4. Formulating the shape of the drill groove and calculating the optimum grinding position of the drill tip by inserting data of the blade groove edge position obtained by performing image processing on the mathematical formula stored in advance by the arithmetic and control unit, The drill tip grinding machine according to any one of claims 1 to 3, wherein the drill is positioned based on the calculation result.