JPS6357108A - Drill breakage detector - Google Patents

Abstract

PURPOSE:To detect drill breakage without fail even if each drill diameter differs, by installing plural optical fibers in group receiving reflected light from a drill, while providing an operational device, and finding drill breakage data from a combination of the reflected light quantities. CONSTITUTION:Both first and second fiber groups 10 and 11 consisting of a pair of bundles of a light emitting optical fiber and a light receiving optical fiber are installed, while the first threshold value conformed to a breakage quantity l1 of a drill 2a in a diameter R1 and the second threshold value conformed to a breakage quantity l2 of a drill 2b in a diameter R2 (R1>R2) are installed. And, the first threshold value is compared with a first electric signal of the first optical fiber group 10 at an operation part 16, and simultaneously it is compared with a second electric signal of the second optical fiber group 11. In consequence of the operation 16, if any of electric signals is lower than these first and second threshold values, it means that there is breakage and the breakage quantity is more than l1, and if it is dropped to only the second threshold value, it is so judged that there is breakage in the drill 2a and the breakage quantity l is l1>l>l2.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an improvement in a drill breakage detection device.

(Conventional technique<ti) For example, drilling a hole in a printed circuit board using a drill is
With the development of printed circuit board manufacturing technology, the diameter is becoming smaller. In the past, a drill with a length of 1 m or more was used, but recently, drilling with a drill of 1 lll to 0.3111 m has been put into practical use.

When performing this hole drilling process automatically based on NG data, it is important to immediately detect any abnormality caused by damage to the drill or breakage such as cutting, and manage it so that it does not proceed to the next process. It is to be.

Due to this need, many methods for detecting breakage of tools such as drills have been considered. As an example, the breakage detection method applied to small diameter drills smaller than T1 involves guiding light through an optical fiber, irradiating it to the tip of the drill, and receiving the reflected light from the drill with the optical fiber. There is a method of detecting drill breakage by determining whether or not there is reflected light at this time, that is, if there is reflected light, it is determined that the drill is not broken, and if there is no reflected light, it is determined that the drill is broken.

However, when drilling holes in printed circuit boards, etc., drills with different diameters are replaced depending on the size of the hole. However, since the optical fiber is installed in a fixed position, the irradiation position on the drill is fixed, and the amount of drill breakage varies depending on the diameter, so it may not be possible to detect drill breakage. In particular, it is difficult to reliably detect drill breakage for drills with greatly different drill diameters.

(Problems to be Solved by the Invention) ``Drill breakage could not be reliably detected for various drills having greatly different drill diameters.

SUMMARY OF THE INVENTION In order to solve the above problems, it is an object of the present invention to provide a drill breakage detection device 81 that can reliably detect a drill breakage even if the drill diameters are different.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a plurality of lights that guide light from a light source, respectively irradiate different parts of a drill, and receive reflected light from the drill. This drill breakage detection device attempts to achieve the above object by providing a group of optical fibers and a breakage data calculation means for obtaining drill breakage data from a combination of the amounts of reflected light guided by the optical fiber group.

(Function) By providing such a means, drill breakage data regarding drill breakage and the amount of breakage can be obtained by combining electrical signals of levels corresponding to the amount of reflected light from the drill.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a case where the drill breakage detection device is applied to a printed circuit board drilling machine, and the printed circuit board 1 is placed on a base, for example, an X-Y table (not shown). This X-Y table moves the drilling by the drill 2 in the process order and processing order according to the pre-programmed NC data etc.
f1lH is to be performed. By the way, this device is a configuration example using a printed circuit board 1 with a drill 2 of 1 mmg and a lower drill 2, for example, a drill 2 of 0.3IllIIl, and this drill 2 is chucked to a rotating main shaft 3, and this main shaft 3 is It is attached to a moving slider 4. The slider 4 is provided to slide within a cylindrical pressure foot 5, and an annular collar 6 is integrally attached to the bottom of the slider 4. An annular foot portion 7 is provided so as to engage with the inner end of this r46, and by moving the pressure foot 5 downward, the foot portion 7 is inserted through i6.
The structure is such that the printed circuit board 1 can be fixed by moving the printed circuit board 1 downward. Therefore, with the printed circuit board 1 fixed, the slider 4 is moved upward, and the drill 2 is perpendicularly incident on the printed circuit board 1 at the position determined by the NC data to perform drilling. There is. After drilling a hole, the drill 2 is placed at a predetermined position where the tip of the drill 2 is separated from the printed circuit board 1 during the period until the next hole is moved to the working position.
It is designed to detect breakage.

Now, in the collar 6 and the foot part 7, each optical fiber H10, which is a pair bundle of a light emitting optical fiber and a light receiving optical fiber, is attached.
, 11 are provided such that one end thereof is obliquely intersecting the tip of the drill 2. FIG. 2 shows a sectional view taken along line A-A'. Note that one end of each optical fiber group 10.11 and the tip of the drill 2 are
When the slider 4 is located at the bottom dead center, the position is set so that there is no interference. And each optical fiber group 10.1
A photoelectric and electro-optical converter 12 is provided at the other end of the optical fiber group 10, and the converter 12 converts the light guided to the light emitting optical fibers of each optical fiber group 10. A photoelectric conversion element 14 is provided. Therefore, the light guided by the light emitting optical fibers of each optical fiber group 10.11 is irradiated onto the tip of the drill 2, and the reflected light is received by the light receiving optical fibers.

By the way, FIG. 3 is a diagram showing the detectable area of the light-receiving optical fiber that receives the reflected light from the tip of the nitrile 2, in which the horizontal axis is the axial position of the light-receiving optical fiber, and the a-axis is the position of the light receiving surface of the light receiving optical fiber in the direction perpendicular to the axial direction of the optical fiber. From the same figure, when the tip of the drill is located on a plane composed of the fiber glaze and the axis perpendicular to this, the optical fiber for light reception is the drill 2.
The detection area that receives the reflected light from is the area surrounded by curve 1. That is, if the drill 2 exists within the area surrounded by the curve l1lW1, the light receiving optical fiber detects the reflected light. Note that the dashed-dotted line indicates the optical fiber axis H. Further, when the drill 2 is broken and the tip of the drill 2 is retreated upward from the optical fiber axis)H, the detectable area by the light-receiving optical fiber is the area surrounded by the curve W2.

Therefore, breakage detection is performed by providing each optical fiber group 10, 11, which is a bundle of a light-emitting optical fiber and a light-receiving optical fiber, in a positional relationship that satisfies the conditions shown in FIG.

Each of the first and second electrical signals for each optical fiber group 10.11 output from the photoelectric conversion element 13 is amplified by the amplifier unit 15 and sent to the breakage data calculation section 16. This breakage data calculation unit 16 inputs the first
The second electric signal level is compared with each of the set first and second threshold values, and the comparison results are converted into digital data to determine whether or not the drill is broken and the amount of drill breakage. Specifically, the first threshold value corresponding to the broken scale 1 of the drill 2a with the diameter R1 shown in FIG. 4(a) and the diameter R2 (R1
>R2) No. 212 corresponding to the amount of breakage 22 of the drill 2b
i! The first threshold value and the first electrical signal of the optical fiber group 10 are compared, and at the same time, the first threshold value and the second electrical signal of the optical fiber group 11 are compared. and,
As a result of this comparison, the electrical signal level of both the first and second I
If it is lower than Jl value, there is a breakage and the amount of breakage 2 is λIL
1. If the value is above and it decreases only with respect to the second threshold value, then the drill 2a is broken and the breakage m is 1.2.
1>Q>Q2. The breakage data reporting unit 17 indicates the broken drill 2.
a, 2b and an eyelid to notify the amount of breakage 2 thereof, and the breakage detection section 18 has the ability to send an abnormal signal to the board hole opening when the breakage occurs. Note that drilling with the drill 2 generates chips, but in order to prevent these chips from adhering to the tips of the optical fiber groups 10 and 11, cleaning is performed from the side wall of the pressure foot 5 through the collar 6. An air outlet 19 is formed for each optical fiber l! Cleaning air is ejected toward the tip of the 110.11. In this case, a suction port may be used instead of the jet port 19 to suck the chips.

Next, the operation and effect will be explained with reference to FIG.

Each time the X-Y table is moved based on the NC data and the position of the hole in the printed circuit board 1 is determined, the pressure foot 5 is lowered at the timing shown in FIG.
to fix the printed circuit board 1. And foot part 7
slider 4 from the time it comes in contact with printed circuit board 1 and is fixed.
is lowered to perform drilling work at the determined position on the printed circuit board 1. After this work, the slider 4 is raised to prepare for the next drilling work. Drill breakage detection is performed during the rising period of the slider 4, which is the preparation period.

That is, light is irradiated onto the tip of the drill 2 from each of the light projecting optical fibers 10 and 11 of the optical fibers 10 and 11. This irradiation light causes scattered light at the tip of the drill 2, and a part of it is incident on each light-receiving optical fiber of each optical fiber group 10.11 as reflected light. Here, if the drill 2 is broken, the incidence of reflected light is either absent or significantly reduced. Therefore, the reflected light received by each optical fiber group 10, 11 is guided to the photoelectric conversion element 13 and converted into first and second electrical signals having a level corresponding to the reflected light H. These electrical signals are then amplified by the amplifier unit 15 and sent to the breakage data calculation section 16.

Now, this breakage data calculation section 16 receives the first electric signal and the first electric signal.
The second electric signal is compared with the second threshold value and the second electric signal is compared with the second threshold value. Here, the drill 2a is being used and the first and second
If the electrical signal levels are lower than the first and second thresholds, it is determined that the drill 2a is broken and the amount of breakage is 21 or more. Further, if the drill 2b is used and only the second electric signal level is lower than the second threshold, the drill 2b
It is determined that the breakage temperature is 1>, 2>, 1. Note that if both the first and second electric signals are lower than the first and second threshold values while the drill 2b is being used, it is determined that the drill 2b is broken and the number of broken points is 21 or more. Then, the result of this judgment is notified by the breakage data notifying section 17, and when a breakage occurs, an abnormality signal is sent from the breakage detection section 18 and the printed circuit board drilling machine is stopped.

In this way, in the above embodiment, the optical fiber group 10
．． 11 is provided, and the presence or absence of drill breakage and its broken surface are determined by the first and second electrical signals of the level corresponding to the number of reflected lights from the drill 2 guided by these optical fiber groups 10 and 11. Even if the diameters of the two diameters are different, minute breaks can be reliably detected for each diameter, and furthermore, the breakage l can be determined.

Note that the present invention is not limited to the above-mentioned embodiment, and may be modified without departing from the spirit thereof. For example, the number of optical fiber groups is not limited to two, but may be provided depending on the type of drill diameter to be used, so that breakage detection can be performed for various drill diameters.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a drill breakage detection device that can reliably detect drill breakage even if the drill diameters are different.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram when an example of the drill breakage detection device according to the present invention is applied to a printed circuit board hole.
The figure is a sectional view taken along the line A-A shown in Figure 1, Figure 3 is a diagram for explaining the detectable area of the optical fiber, and Figures 4 (a) and (b).
) is a diagram for explaining the operation of detecting drill breakage, and FIG. 5 is a timing chart for explaining the operation and operation of the apparatus of the present invention. 1... Printed circuit board, 2... Drill, 3... Spindle. 4... Slider, 5... Cylindrical pressure shaft, 6... Tsuba, 7... Foot portion, 10.11...
Optical fiber group, 12...Photoelectric-electronic converter, 15...
・Amplifier unit, 16...Breakage data calculation section, 17
...Breakage data reporting section, 18...Breakage detection section. Applicant's representative Patent attorney Takehiko Suzue Figure 2 Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) A plurality of optical fiber groups that guide light from a light source, respectively irradiate this light to different parts of the drill, and receive the reflected light from the drill, and A drill breakage detection device comprising breakage data calculation means for calculating drill breakage data from each combination of light amounts. (2) The drill breakage detection device according to claim (1), wherein the breakage data calculation means determines whether or not the drill is broken and the amount of drill breakage.