JP2003315022A - Method for inspecting depth in non-through hole - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a depth inspection method of a non-through hole that can arbitrarily set the depth of the non-through hole and can save facility investment. <P>SOLUTION: A first inspection 1 having a plate thickness T2 being equivalent to the allowable maximum value, and a first inspection section C1 having a plate thickness T1 being equivalent to the allowable minimum value of a punch depth, are formed first at the end section of a workpiece 1 in a preliminary process. In a next punching process, a through hole 20 is formed at the first inspection section C1, and a non-through hole 21 is formed at the second inspection section C2, thus also punching a machining section B under the same conditions. Then, regardless of the thickness of the machining section B, the depth of the non-through hole 21 can be set freely. In the inspection process, it is easily and inexpensively understood that the depth of the non-through hole 21 is within an allowable range Tt if the transmission light exists only at the first inspection section and there is no transmission light at the second inspection section C2. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of inspection technology for inspecting the depth of non-through holes (so-called blind holes) formed in a work. INDUSTRIAL APPLICABILITY According to the present invention, the depth of the non-penetrating hole is difficult to be uniquely determined as in the case of drilling with a laser, a water jet, an electron beam, an ion beam or a plasma jet without using a drill or a needle in the drilling process. This is especially effective in the case.

[0002]

2. Description of the Related Art As prior art 1, as shown in FIG. 7, when a work is perforated with a laser beam and transmitted light leaking from the tip of the hole being perforated to the back side of the work is detected by an optical sensor. There was a way to stop the perforations. Such a method is disclosed in Japanese Patent Laid-Open No. 10-85966.

However, in such a punching method, the laser beam is transmitted to the back side of the work and leaks to such an extent that
It is necessary that the tip of the non-through hole be close to the back surface of the work. Therefore, the depth of the non-penetrating hole cannot help setting the depth of the non-penetrating hole arbitrarily because the depth of the non-penetrating hole has to be in a stopped state immediately before penetration.

Further, in order to precisely stop the depth of the non-through hole, a feedback control device from an optical sensor is required, and this feedback system is expensive, so the facility investment is expensive. It was

Therefore, in order to solve the inconvenience that the depth of the non-through hole cannot be freely set, Japanese Patent Laid-Open No. 2000-2054 has been proposed.
Japanese Patent No. 66 discloses a technique (prior art 2) in which a processing laser pulse and a measurement laser pulse are emitted substantially coaxially so that the two laser pulses do not interfere with each other.

In this prior art 2, not only the depth of the non-through hole can be set arbitrarily, but also since the depth is measured in parallel with the drilling, the non-through hole does not become too deep. But it was an excellent technique. However, since the measuring laser pulse device and the control device for synchronizing both laser pulses are required, the conventional technique 2 also has a disadvantage that the capital investment tends to be slightly expensive. .

As a reference technique, Japanese Patent Laid-Open No. 2000-2
Japanese Patent No. 38603 discloses a technique for optically confirming that the tip of a needle hole penetrates a member. However, since this technique cannot be applied to non-through holes, it is considered to be out of the prior art of the present invention.

Further, the technique disclosed in the above publication has the following two disadvantages when it is applied to an application for forming a lid that causes a breakage of an airbag. Firstly, since the needle (puncture needle) is used to pierce the resin plate as the work, swelling occurs around the root opening of the through hole on the surface side to be pierced, and this swelling becomes debris when the airbag is deployed. It is inconvenient for occupant protection to be scattered. Secondly, in the needle perforation, the inner diameter of the through hole is inevitably larger than that of the laser perforation, so that the distance between adjacent through holes must be increased. As a result, the fractured part between the through-holes becomes large, which makes it easier for fragments to fly when the airbag is deployed, and also makes the jagged protrusions on the fracture surface large for occupant protection. It is inconvenient.

[0009]

Therefore, unlike the prior art 1, the present invention is capable of arbitrarily setting the depth of the non-through hole, but is more suitable for processing equipment than the prior arts 1 and 2. It is an issue to be solved to provide a “non-through hole depth inspection method” which can reduce the investment cost.

[0010]

In order to solve the above problems, the inventor has invented the following means.

(First Means) The first means of the present invention is a boring step of forming a non-penetrating hole from the surface to a predetermined depth inside the processed portion of the work, the surface of the work and the surface thereof. Of the non-penetrating hole, which includes irradiating light toward one side of the back surface facing back to and observing light leaking from the other side and inspecting the depth of this hole. However, the applicant does not regard this as a known precondition. This is because a document disclosing a technique of irradiating light from the back surface of the work and detecting light leaking from the opening of the hole on the surface has not been found at least by the investigation by the inventor and the applicant.

Here, the front surface and the back surface in the processed portion of the work are a front surface and a back surface for convenience in the punching step,
It has nothing to do with the front and back in other states such as the state in which the product is used.

The main features of this means are the following three points.

First, in addition to the above-described punching step and inspection step, a preliminary step is further provided.
This preparatory step is an inspection area in which a part of the work has a predetermined thickness equal to or less than the thickness of the perforated portion of the non-through hole,
This is a step of providing an inspection part which is made of the same material as the work and at least a part of which is at least one of the test pieces having a predetermined thickness thinner than the perforated portion of the non-through hole.

That is, the inspection section is usually one of the inspection area which is a part of the work and is integral with the processing section, and the test piece which is separate from the work having the processing section. is there. Whether the inspection portion is an inspection region or a test piece, the inspection portion is made of the same material that has at least the same properties as those of the processed portion, and the thickness of the inspection portion is the same as that of the processed portion. It is less than or less than the thickness.

Secondly, the perforating step is a step of perforating the inspection section under the same conditions as the processing section.

Thirdly, in the inspection step, after the preliminary step, the light leaked from the one side of the inspection section to the other side is observed, and the depth of the non-through hole in the processed section and the inspection are performed. That is, it is a step of determining the length and the thickness of the portion.

Here, regardless of the order of the preliminary step and the punching step, the punching step may be performed after the preliminary step, or conversely, the preliminary step may be performed after the punching step. Alternatively, there is also a manufacturing method in which a non-through hole is formed at the same time when the work is molded, and the preliminary step and the punching step may be performed at the same time.

The inspection process is usually performed after the perforation process, but the inspection process is not limited to this. That is, if the laser beam is simultaneously observed from the back surface while laser perforation is performed in the perforation step, the perforation step and the inspection step are performed simultaneously. When the processing section and the inspection section are separate parts, the punching step and the inspection step are performed in tandem. At this time, if the inspection unit is first drilled, the inspection process is performed prior to the drilling process. On the contrary, when the processing section and the inspection section partially overlap, the inspection step is performed at the same time as at least a part of the punching step.

As suggested in this description, when the inspection part is the inspection region which is a part of the work, at least a part of the processed part may overlap with the inspection part.

With this means, in the punching step, the inspection section is also punched under the same conditions as the processing section. Therefore, the inspection portion is perforated at the same depth as the processed portion. As a result, if the depth of the non-through hole in the processed part is shallower than the thickness of the perforated part of the inspection part, the non-through hole is also formed in the inspection part, and conversely it is deeper than the thickness of the perforated part of the inspection part. For example, a through hole is formed in the inspection part. That is, when the depth of the hole formed in the inspection portion is shallower than the thickness of the inspection portion, meat remains on the other side of the inspection portion and becomes a non-through hole. On the contrary, when the depth of this hole is deeper than the thickness of the inspection part, the hole penetrates the inspection part in the perforation step, and this hole becomes a through hole.

In the inspection step, light is emitted from one of the front and back sides of the perforated inspection section, and the light leaked from the other of the inspection sections is observed. Then, unless the work is made of a transparent material, the light is not detected if the hole drilled in the inspection part is a non-through hole. Therefore, this shows that the depth of the non-through holes in the processed portion is shallower than the thickness of the inspection portion. On the other hand, if the through hole is opened in the inspection part, the light passing through the through hole is detected. Therefore, the depth of the non-through hole of the processed part is deeper than the thickness of the inspection part. I understand.

That is, as described above, since the processed portion and the inspection portion are perforated under the same conditions, it can be estimated with confidence that the perforation depths are the same. Therefore, if the inspection portion is perforated and it is determined through light whether or not the hole has penetrated the inspection portion, then the thickness of the perforated portion of the inspection portion and the depth of the non-through holes formed in the processed portion You can tell which one is thicker or thinner and whether it is long or short. In this way, if the thickness of the inspection part is properly set, the depth of the non-through hole formed in the processed part depends on whether the hole opened in the punching process penetrates the inspection part. It becomes extremely easy to determine whether the length is shorter or shorter than that.

Moreover, according to this method, unlike the above-mentioned Prior Art 1, since it is not necessary to set the depth of the through hole to the stopping state immediately before the penetration, the thickness of the processed portion can be arbitrarily set. It becomes possible to inspect the set depth of the non-through hole.

In addition, the above-mentioned prior art 1 and prior art 2
Unlike the above, an expensive control device that feedback-controls the punching device based on the amount of light detected by the optical sensor is unnecessary, and the punching process can be performed without feedback. As a result, the time required for the drilling process can be shortened, and the capital investment of the drilling system used for the drilling process is significantly reduced. Specifically, the inventor
The capital investment required to construct the drilling system is expected to be cut in half or 70%.

Therefore, according to the non-through hole depth inspection method of the present means, the following three effects can be obtained.

First, unlike the above-mentioned Prior Art 1, since it is not necessary to set the depth of the non-through hole in the processed portion to a stop state immediately before the penetration, the thickness of the processed portion can be arbitrarily set. There is an effect that it becomes possible to inspect the set depth of the non-through hole.

Secondly, unlike the prior art 1 and the prior art 2, the drilling process can be performed without feedback, so that the time required for the drilling process can be shortened.

Thirdly, unlike the prior art 1 and the prior art 2, since the feedback control device is not required, there is an effect that the equipment investment of the drilling system used in the drilling process is significantly reduced.

(Second Means) A second means of the present invention is the first means according to the above-mentioned first means, wherein the inspection portion has a thickness corresponding to an allowable minimum value of the predetermined depth of the non-penetrating hole. At least one of the inspection unit and the second inspection unit having a thickness corresponding to the allowable maximum value of the predetermined depth of the non-through hole is provided.

According to this means, it is possible to determine whether or not the depth of the non-through hole in the processed portion exceeds the allowable minimum value by optically detecting whether or not the through hole is opened in the first inspection portion. . Similarly, if it is detected whether the through hole is opened in the second inspection unit,
It is possible to determine whether or not the depth of the non-through hole in the processed portion exceeds the maximum allowable value.

Therefore, when both the first inspection part and the second inspection part are provided in the inspection part, it is highly reliable that the depth of the non-through hole in the processed part is within a predetermined allowable range. It is desirable to estimate with. That is, if a relatively thin first inspection portion has a through hole formed therein, while a relatively thick second inspection portion has a non-through hole formed therein, the non-through hole formed in the processed portion is formed. It can be seen that the depth of is within the allowable range between the allowable minimum value and the allowable maximum value. Therefore, if the inspection section has both the first inspection section and the second inspection section, the inspection section indirectly inspects that the depth of the non-through hole is within the allowable range of the dimensional tolerance in the processed section. be able to.

On the contrary, if the first inspection portion having a thickness corresponding to the allowable minimum value of the depth of the non-penetrating hole is not penetrated and the non-penetrating hole is formed, the machining is performed. It can be seen that even in the portion, the depth of the non-penetrating holes is too shallow so as not to reach the allowable minimum value. On the other hand, the hole has penetrated into the second inspection part having a thickness corresponding to the maximum allowable depth of the non-through hole,
It can be seen that when the through hole is formed, the depth of the non-through hole exceeds the allowable maximum value and is too deep even in the processed portion. In either case, the workpiece will be removed from the product as a defective product that does not meet the dimensional tolerance.

There may be a case where only one of the first inspection section and the second inspection section is provided in the inspection section. Of course, the presence of only the first inspection portion is appropriate when the depth of the non-through hole in the processed portion exceeds the allowable minimum value and the non-through hole may be somewhat deeper. On the contrary, having only the second inspection part is suitable when the depth of the non-penetrating hole in the processed part does not have to reach the maximum allowable value and the non-penetrating hole may be somewhat shallow. is there.

As an aside, the processing section may serve as either the first inspection section or the second inspection section. In the case where the processed portion also serves as the first inspection portion, it is likely that all the processed portions have through holes (outside the scope of the present invention).
On the contrary, when the processed part also serves as the second inspection part, the optical inspection is performed on all the perforated parts of the processed part, so that the processed part has no through holes and the holes formed in the processed part are It is guaranteed to be all non-through holes.

Therefore, according to this means, in addition to the effect of the above-mentioned first means, in the dimensional tolerance of the depth of the non-through hole,
There is an effect that at least one of the allowable minimum value and the allowable maximum value is guaranteed.

(Third Means) The third means of the present invention is the above-mentioned first means, wherein the inspection portion has a continuous thickness within a range that covers an allowable range of the predetermined depth of the non-through hole. It is a tilt inspection part that changes in a stepwise or stepwise manner, and the punching step is a step of punching a plurality of portions of the tilt inspection part having different thicknesses.

In this means, the inspection unit is the inclination inspection unit,
Since a plurality of portions having different thicknesses are punched under the same conditions as the machined portion, it is possible to more accurately estimate the depth of the non-through holes formed in the machined portion.

For example, in the above-mentioned second means, there is a portion having a three-step difference in thickness between the first inspection portion and the second inspection portion, and there is a portion from the first inspection portion to the second inspection portion. Let us assume that the thickness of the tilt inspection part is divided into five levels. Of course, it is assumed that the inspection section at any stage is perforated under the same conditions as the processing section in the perforation step. Then, in the inspection process, the depth of the non-through hole in the processed part can be grasped in approximately five stages by inspecting how thick the hole penetrates in the tilt inspection part. Become.

Alternatively, the inspection section is an inclination inspection section whose thickness continuously changes within a range that covers the permissible range of the depth of the non-through holes, and in the perforation step, a large number of holes are formed along the inclination direction. Assumed to be worn. Then, by inspecting how thick the hole penetrates in the tilt inspection portion, the depth of the non-penetrating hole formed in the processed portion can be estimated in a fairly fine and stepwise manner.

For example, the thickness of the inclined inspection portion is tapered by continuously forming a flat inclined surface from a thickness slightly exceeding the maximum allowable value of the non-through holes to a thickness slightly less than the minimum allowable value. Let's do it. If 100 holes are drilled at equal intervals in this range, the depth of the non-through hole formed in the machined part can be reduced to about 100 by inspecting the thickness of the transition from the non-through hole to the through hole. It is possible to estimate in stages.

In any case, if the work has already been drilled in the drilling step, the work cannot be handled, but it is possible to know how much the drilling depth of the next work should be adjusted. In the next work, the depth of the non-through hole can be adjusted to a more appropriate degree. However, in the drilling process, starting the drilling from the inclination inspection unit before the processing unit,
If the inspection step is performed in parallel with the perforation step as in the following fourth means, the inspection result can be reflected in the perforation depth of the machined portion of the work itself.

Therefore, according to this means, in addition to the effect of the above-mentioned first means, it becomes possible to estimate the perforation depth of the non-penetrating hole formed in the machined portion at a desired stage accuracy, and as a result, Therefore, there is an effect that it becomes possible to appropriately adjust the depth of the drilling in the drilling step.

(Fourth Means) According to a fourth means of the present invention, in the above-mentioned first means, the perforating step is a step of perforating the work with a laser beam, and in the inspecting step, the laser beam is applied to the work. It is a step of detecting whether or not the inspection portion is penetrated.

In the present means, when the inspection portion of the work is laser-perforated in the perforation step, an inspection step for detecting whether or not the laser beam penetrates the inspection portion is performed in parallel with this. Therefore, it is not necessary to separately perform the inspection process after the punching process, and the number of steps is reduced accordingly.

Therefore, according to this means, in addition to the effect of the above-mentioned first means, the number of man-hours as a whole of the punching process and the inspection process is reduced, and the punching process and the inspection thereof proceed faster.

(Fifth Means) According to a fifth means of the present invention, in the above-mentioned first means, in the inspecting step, the light leaked from the inspecting section is divided into a semitransparent body having a scattering property and a diffuse reflection surface. It is characterized by a step of receiving light by any one of the scattering means and detecting scattered light diverged from the scattering means.

Here, as the scattering semi-transparent material, there are ground glass, tracing paper, a white thin resin sheet, and the like, and if it is extreme theory, white thin paper may be used. on the other hand,
As the scattering diffuse reflection surface, there is a white ceramic plate, a plate material coated with white, or the like, and white paper may be used as far as possible.

In this means, the light received through the through hole opened in the inspection portion of the work is not directly detected but the scattered light is detected, so that the light receiving range is expanded. As a result, even if the inspector visually inspects, or CC
Even when inspecting automatically with an optical sensor such as D,
The allowable range of the position of the light receiving portion (that is, the inspector's naked eye or the optical sensor) is expanded. As a result, the robustness of the position of the light receiving unit is improved, and the reliability of the inspection is increased. Especially when the inspector is inspecting with the naked eye, it is difficult to fix the light receiving part like an optical sensor.
Even if the inspector moves his or her head considerably, the inspector can still visually check it, and the effect of reducing fatigue of the inspector is great.

Therefore, according to this means, in addition to the effect of the above-mentioned first means, there is an effect that the naked eye of the inspector and the light receiving range of the optical sensor are expanded. As a result, there is an effect that the reliability of the inspection is improved and a high fatigue reducing effect is obtained especially in the case of the visual inspection by the inspector.

[0051]

BEST MODE FOR CARRYING OUT THE INVENTION A mode for carrying out the "non-through hole depth inspection method" of the present invention will be clearly and sufficiently described in the following examples so that those skilled in the art can understand the invention. .

[Embodiment 1] (Structure of Embodiment 1) As a first embodiment of the present invention, a method of inspecting a depth of a non-through hole is as follows.
To form a non-penetrating hole 21 reaching a predetermined depth therein (see FIG. 1), irradiating the surface 1a of the work 1 with light, and observing light leaking from the other hole And an inspection step (see FIG. 2) for inspecting the depth of.
In the inspection method of the present embodiment, a part of the work 1 is covered with the non-through hole 2.
Predetermined thicknesses T1 and T less than the thickness T0 of the perforated portion 1
The method further includes a preliminary step of providing the inspection unit C, which is the inspection area set to 2.

Here, the perforating step is a step of perforating the inspection section C under the same conditions as the processing section B of the work 1.
On the other hand, in the inspection process, after the preliminary process, the inspection unit C
This is a step of observing the light leaked from the front surface 1a to the back surfaces 1b ′, 1b ″ to determine the length of the depth of the non-through hole 21 in the processed portion B and the thicknesses T1, T2 of the inspection portion C. The inspection portion C has a first inspection portion C1 having a thickness T1 corresponding to an allowable minimum value of a predetermined depth of the non-through hole 21, and a thickness corresponding to an allowable maximum value of a predetermined depth of the non-through hole 21. It has a second inspection unit C2 having T2.

That is, in the present embodiment, first, a forming step of forming the work 1 as a preliminary step, secondly a perforating step of laser-perforating the work 1 (see FIG. 1), and thirdly opening the work 1 It is a method of inspecting the depth of a non-penetrating hole, which includes three steps of an inspection step of optically finding the penetrating hole 20 (see FIG. 2).

First, in the forming step as a preliminary step, as shown in FIG. 1, a processed portion B, which is a portion where a non-through hole 21 having a predetermined depth is to be formed, is provided in the main portion of the work 1. In this step, an inspection portion C, which is an inspection region having a predetermined thickness equal to or less than the thickness of the perforated portion of the non-through hole 21, is provided at the end of the work 1.

The work 1 is a plate material made of polypropylene type thermoplastic resin and formed to a predetermined thickness. The resin forming the work 1 contains a large amount of black fine pigment and is black, and the transparency of the work 1 is extremely low. Then, as shown in FIG. 1, the work 1 has a non-through hole 21.
And the processed portion B, which is the main portion where the
In order to inspect the depth of No. 1, an inspection section C which is provided at the end of the work 1 and has a smaller plate thickness than the processed section B is formed.

Here, the plate thickness T0 of the processed portion B of the work 1 is
Are formed thicker than the maximum allowable depth of the non-through holes 21. Conversely, the allowable maximum value of the depth of the non-through hole 21 is set to be shallower than the plate thickness T0 of the processed portion B. Therefore, the punching process described below is normal, and the non-through hole 21
If the depth does not exceed the permissible maximum value, only the non-through hole 21 is drilled in the processed portion B, and the through hole 20 is not drilled.

On the other hand, the inspection portion C has a first inspection portion C having a thickness T1 corresponding to the allowable minimum value of the predetermined depth of the non-through hole 21.
1 and a second inspection portion C2 having a thickness T2 corresponding to the allowable maximum value of the predetermined depth of the non-through hole 21.

As described above, since the processed portion B and the inspection portion C have different plate thicknesses, the front surface 1a of the work 1 is a flat surface, but the back surface of the work 1 has the back surface 1b of the processed portion B. There is a step between the back surface 1b ′ and 1b ″ of the inspection part C. Further,
In the inspection part C, there is a step between the back surface 1b ′ of the first inspection part C1 and the back surface 1b ″ of the second inspection part C2. Therefore, the thickness of the work 1 is T0), the second inspection portion C2 (thickness T2), and the first inspection portion C1 (thickness T
Although the thickness gradually decreases in the order of 1), steps are gently formed at these step portions so that stress concentration does not occur.

Secondly, as shown in FIG. 1, the punching step is a step of forming a non-penetrating hole 21 extending from the surface 1a of the work 1 to a predetermined depth therein, as shown in FIG. . Then, the perforation step is a step of perforating the inspection section C including the first inspection section C1 and the second inspection section C2 under the same conditions as the processing section B.

Incidentally, in FIG. 1, the first inspection section C1 is schematically shown.
It is designed such that two holes are drilled in each of the second inspection section C2 and the second inspection section C2, but in practice an appropriate number (a few locations)
Is perforated. A slab-type carbon dioxide laser processing machine is used for the perforation, and the processing machine has a large number of non-through holes 21 each having a predetermined diameter and a predetermined range from one end to the other end of the processing portion B. After punching at a predetermined pitch, a plurality of holes are punched in the inspection section C as they are under the same conditions.

Here, when a single non-through hole 21 is drilled in an arbitrary portion of the work 1, the laser beam machine remains at that point, and a short laser pulse is given to the surface 1a of the work 1 a large number of times. From there, it is driven into the work 1 and punched. At this time, the black resin that has been irradiated with the laser instantly rises in temperature at the irradiated portion, is decomposed into vaporized high-temperature gas and carbonized fine particles, and is naturally blown out from the opening at the root of the hole. The depth perforated by one pulse and the perforation diameter are generally determined by the output (wattage) and pulse width (duration) of the laser pulse and the properties of the resin forming the work 1. Therefore, when a laser pulse is irradiated a predetermined number of times on one portion such as the processed portion B, the non-penetrating hole 21 having a predetermined depth is formed although there is variation in a predetermined range. In the root portions of the non-penetrating holes 21 and the penetrating holes 20, the opening diameter on the surface 1a is slightly larger than the inner diameter of the hole inside the work, and a bulge is formed around the opening unlike the needle perforation. It will not be done.

That is, in the drilling process, the inspection part C is also drilled under the same conditions as the processing part B. Therefore, if the drilling process is normal and the drilling depth is within the allowable range or control width Tt. , Like this: First, the non-through hole 21
The second inspection portion C2 having the thickness T2 corresponding to the maximum allowable value of the predetermined depth is drilled from the front surface 1a to just before the back surface 1b ″, and the hole does not penetrate to the back surface 1b ″. The non-through hole 21 is formed in the inspection portion C2. Next, the thickness T1 corresponding to the allowable minimum value of the predetermined depth of the non-through hole 21.
The first inspection part C1 having a hole is pierced from the front surface 1a to the back surface 1b ', and the through hole 20 is opened in the first inspection part C1.

Thirdly, the inspection process is as shown in FIG.
The front surface 1a of the work 1 is irradiated with light, and the rear surfaces 1b, 1
This is a step of inspecting the depth of these holes by observing light leaking from b′1b ″. More specifically, in the inspecting step, the front surface 1a to the back surface 1 of the inspection portion C are performed after the preliminary step.
This is a step of observing the light leaking to b ′, 1b ″ and determining the length of the depth of the non-through hole 21 in the processed portion B and the thickness of the inspection portion C.

That is, in the inspection process, a straight rod-shaped fluorescent lamp FL is used as a light source for inspection, and an inspector observes light leaking through the through hole 20 of the work 1 with the naked eye E, and the depth of the non-through hole 21. A visual judgment is made as to whether or not is within an appropriate range. The work 1 is placed between the fluorescent lamp FL and the inspector's naked eye E so that the light from the fluorescent lamp FL is incident on the inspector's naked eye E through the through hole 20 in the position and the posture.

As a result, the light of the fluorescent lamp FL can be visually confirmed from the portion where the through hole 20 is formed in the inspection portion C, and the light cannot be visually observed at the portion where the non-through hole 21 is formed. The non-through hole 21 and the through hole 20 can be instantly distinguished from each other. Then, only when the through holes 20 are opened at all predetermined positions in the first inspection unit C1 and the light can be visually recognized, and conversely, the light cannot be visually recognized in the second inspection unit C2,
The inspection result of the work 1 is passed. In other cases, it is estimated that the depth of the non-through hole 21 in the processed portion B does not fall within the predetermined allowable range Tt, and the inspection result is rejected. Can be managed.

In this embodiment, not only the first inspection section C1 and the second inspection section C2 but also the processed section B is visually inspected. This is because an exceptional defect has occurred
This is to confirm that the holes do not penetrate.

(Effects of Embodiment 1) Since the method for inspecting the depth of a non-through hole according to this embodiment is configured as described above, it has the following effects.

First, in the punching step, as shown in FIG. 1 again, the inspection section C is under the same conditions as the processing section B as described above.
Since the laser drilling is also performed, a hole is drilled at the same depth as the processed portion B in the inspection portion C including the first inspection portion C1 and the second inspection portion C2. As a result, if the depth of the non-through hole 21 in the processed portion B is smaller than the thickness of the perforated portion of the inspection portion C, the non-through hole 21 is also formed in the inspection portion C. vice versa,
If the perforation depth is deeper than the thickness of the inspection portion C, the through hole 20 is formed in the inspection portion C. That is, when the depth of the hole formed in the inspection part C is shallower than the thickness of the inspection part C,
In the inspection portion C, meat is left on the back surface 1b ″ side and the non-through hole 21
Is formed. On the contrary, when the depth of perforation is deeper than the thickness of the inspection part C, the hole also penetrates the back surface 1b ′ of the inspection part C in the perforation step, and this hole becomes the through hole 20.

Next, in the inspection step, as shown in FIG. 2 again, the fluorescent lamp FL is inserted from the side of the surface 1a of the inspected inspection portion C.
The back surface 1 of the inspection part C is irradiated with light through the through hole 20.
The inspector visually observes the light leaked from b ′, 1b ″ with the naked eye E. Then, since the work 1 is made of the black resin that hardly transmits light as described above, the hole drilled in the inspection part C is formed. The light is not visually recognized if is the non-through hole 21. Therefore, the second inspection portion C2 of the inspection portion C is thus confirmed.
It can be seen that the depth of perforation of the non-through holes 21 in the processed portion B is shallower than the thickness thereof. On the other hand, since the through hole 20 is opened in the first inspection portion C1 of the inspection portion C, the through hole 2
Since the light that has passed through 0 is visually recognized, it can be understood from this fact that the depth of the non-through holes 21 of the processed portion B is deeper than the thickness of the first inspection portion C1.

That is, as described above, the material of the work 1 is the same in the processed portion B and the inspection portion C, and laser drilling is performed under the same conditions, so the depth to be drilled varies by a predetermined amount. It can be estimated with confidence that they are equivalent within the range of. Therefore, if the inspection portion C is drilled and it is determined through light whether or not the hole penetrates the inspection portion C, the thickness of the punched portion of the inspection portion C and the non-through holes 21 formed in the processed portion B are determined. It is possible to determine whether the thickness is thick or thin among the depths. Thus, if the thickness of the inspection portion C is properly set, the depth of the non-penetrating hole 21 formed in the processed portion B depends on whether or not the hole opened in the perforation step penetrates the inspection portion C. It becomes extremely easy to determine whether the thickness is longer or shorter than the thickness of the inspection portion C.

Further, the inspection portion C is formed in the processing portion B and the first inspection portion C1 having the thickness T1 corresponding to the allowable minimum value of the depth of the non-through hole 21 to be formed in the processing portion B. Thickness T2 corresponding to the maximum allowable depth of the non-through hole 21 to be formed
And a second inspection unit C2 having Therefore, by optically detecting whether or not the through hole 20 is opened in the first inspection portion C1, it is determined whether or not the depth of the non-through hole 21 in the processed portion B exceeds the allowable minimum value T1. it can. Similarly, if the second inspection portion C2 detects whether or not the through hole 20 is opened, it can be determined whether or not the depth of the non-through hole 21 in the processed portion B exceeds the allowable maximum value T2. it can.

In other words, since both the first inspection portion C1 and the second inspection portion C2 are provided in the inspection portion C, the depth of the non-through hole 21 in the processed portion B falls within the predetermined allowable range Tt. Can be estimated with high reliability. That is, the first inspection part C having a relatively thin plate thickness T1
1 has a through hole 20 formed therein, while a second inspection portion C2 having a relatively thick plate thickness T2 has a non-penetrated hole 21 formed therein, the non-penetrating portion formed in the processed portion B is not formed. Hole 2
It can be seen that the depth of 1 is within the allowable range Tt between the minimum allowable value T1 and the maximum allowable value T2. as a result,
Since the inspection section C is provided with both the first inspection section C1 and the second inspection section C2, the inspection section also confirms that the depth of the non-through hole 21 is within the allowable range Tt of the dimensional tolerance in the processed section B as well. It can be indirectly inspected and guaranteed by C.

This also means that, as shown in FIG. 2, the tip of the non-through hole 21 drilled in the processed portion B is within the allowable range Tt between the allowable minimum value T1 and the allowable maximum value T2. It is clear from that.

On the contrary, when the first inspection portion C1 having the thickness T1 corresponding to the allowable minimum value of the depth of the non-through hole 21 is not penetrated and the non-through hole 21 is formed. It can be seen that even in the processed portion B, the depth of the non-through hole 21 is too shallow so as not to reach the allowable minimum value. On the other hand, if the second inspection portion C2 having a thickness corresponding to the allowable maximum value T2 of the depth of the non-through hole 21 penetrates the hole and the through hole 20 is formed, processing is performed. It can be seen that also in the portion B, the depth of the non-through holes 21 exceeds the allowable maximum value and is too deep. Alternatively, if at least one through hole 20 is formed in the first inspection portion C1 and at least one non-through hole 21 is formed in the second inspection portion C2, the non-through hole in the processed portion B is not formed. It can be seen that the perforation depths of the through holes 21 vary widely and are not within the allowable range or the management width Tt. In any case, the work 1 may be removed from the processing line without waiting for it to be a product, as a defective product that does not satisfy the dimensional tolerance of the non-through hole 21.

Further, according to the present embodiment, unlike the above-mentioned Prior Art 1, since it is not necessary to set the depth of the through hole 20 to a stop state immediately before the penetration, the thickness of the processed portion B is By doing so, the depth of the non-through hole 21 set arbitrarily can be inspected.

Further, the above-mentioned prior art 1 and prior art 2
Unlike the above, an expensive control device that feedback-controls the punching device based on the amount of light detected by the optical sensor is unnecessary, and the punching process can be performed without feedback. As a result, the time required for the drilling process can be shortened, and the capital investment of the drilling system used for the drilling process is significantly reduced. Specifically, the inventor expects that the equipment investment required for constructing a drilling system will be halved.

According to the experiment conducted by the inventor,
It is known that the visual confirmation with the naked eye E of the inspector can not only make a determination in an extremely short time but also has an extremely high reliability. Therefore, if mass production is not carried out, it is also a powerful option to refrain from capital investment to prepare a complete optical sensor system for determination and rely on visual confirmation by an inspector for the inspection process.

Therefore, according to the method for inspecting the depth of the non-through hole of this embodiment, the following four effects can be obtained.

Firstly, unlike the above-mentioned prior art 1, since it is not necessary to set the depth of the non-through holes 21 in the processed portion B to a stopped state immediately before the penetration, the thickness of the processed portion B is It is possible to inspect the depth of the non-penetrating hole 21 that is arbitrarily set by the above method. Conversely speaking, the thickness T0 of the processed portion B may be designed to be as large as the plate thickness T2 of the second inspection portion C2, and in the extreme, the processed portion B may be a block. There is.

Secondly, there is an effect that the perforation depth of the non-through hole 21 can be easily controlled. That is, the perforation depth of the non-through hole 21 in the processed portion B is the plate thickness T of the first inspection portion C1.
If the allowable range or the control width Tt between 1 and the plate thickness T2 of the second inspection portion C2 is within the range, only products estimated with sufficiently high reliability pass the inspection process. Therefore, defective products related to the depth of perforation of the non-through holes 21 can be easily eliminated in the inspection process.

Thirdly, unlike the prior art 1 and the prior art 2, since the punching step can be performed without feedback, there is an effect that the time required for the punching step can be shortened. As a result, the total time required for the perforation step and the inspection step is approximately half the time required for the perforation step of Conventional Technique 1 and Conventional Technique 2.

Fourthly, unlike the prior art 1 and the prior art 2, since the feedback control device is not required, there is an effect that the equipment investment of the drilling system used in the drilling process is significantly reduced. This effect is expected to be large enough to reduce capital investment by half or to one-third.

If there is no aesthetic or functional inconvenience due to the stepped inspection section C being hidden by the end of the product,
You may leave it as it is. On the contrary, if it is inconvenient to leave the inspection unit C, the inspection unit C may be cut off from the work 1. Or from the beginning, the inspection department C
As a test piece independent of the processing part B of the work 1,
In the piercing process, the work 1 may be laid side by side, and only the test piece may be inspected in the inspection process.

(Modification 1 of Embodiment 1) As Modification 1 of this embodiment, as shown in FIG. 3, in the inspection step, the light leaked from the inspection portion C is treated as a scattering semi-transparent material. It is possible to carry out the method of inspecting the depth of the non-penetrating hole, which is a step of detecting the scattered light which is received by the scattering means made of the frosted glass F and transmitted through the frosted glass F. The frosted glass F is preferably placed close to the back surface 1b of the work 1. However, since the frosted glass F comes into contact with the back surface 1b of the work 1 and becomes dirty, it is placed slightly away from the back surface 1b of the work 1.

In this modification, the first inspection section C of the work 1 is
The light received through the through hole 20 opened in the inspection section C including the first and second inspection sections C2 is not directly observed but the scattered light transmitted through the frosted glass F is observed, so that the light receiving range is expanded. That is, it is sufficient for the inspector to visually check the bright point P on the back surface of the frosted glass F, and even if the inspector visually inspects, the allowable range of the position of the naked eye E of the inspector expands.

As a result, the robustness of the position of the naked eye E of the inspector is improved, and the reliability of the inspection by the inspector is increased. That is, as in the case of the above-described first embodiment, the inspector also inspects with the naked eye E in this modification, and it is difficult to fix the light receiving unit like an optical sensor. However, in this modification, even if the inspector moves his / her head considerably, the bright spot P on the frosted glass F can still be visually confirmed, so that the fatigue reducing effect obtained by the inspector is large.

Therefore, according to this modification, in addition to the effect of the first embodiment described above, there is an effect that the light receiving range of the naked eye E of the inspector is widened and the reliability of the inspection is improved. There is an effect that a high fatigue reducing effect can be obtained.

As the scattering semi-transparent material, a tracing paper, a white thin resin sheet, or the like can be adopted in addition to the frosted glass F, and, as a matter of course, white thin paper may be used. .

On the contrary, instead of the scattering semi-transparent body, the scattering means having the irregular reflection surface may receive the light leaked from the inspection section C and detect the scattered light irregularly reflected from the irregular reflection surface. good. Here, the scattering irregular reflection surface includes a white ceramic plate, a plate material coated with white, or the like, and white paper may be used as far as possible.

At this time, it is desirable to place the irregular reflection surface close to the back surface 1b of the work 1. However, if this is done, there will be no place where the head of the inspector can enter. Since this is inconvenient, it is preferable to incline the diffuse reflection surface by about 45 ° and allow the inspector to look in from the lateral direction (from the direction perpendicular to the paper surface of FIG. 2).

As a light source for inspection, a single fluorescent lamp F is used.
It is preferable to use not only L but also a plurality of fluorescent lamps or electric lamps as the inspection light source, and place a scattering transmission plate such as ground glass F between the inspection light source and the work 1. This makes it possible to deal with the case where the non-through holes 21 and the through holes 20 of the inspection section C are not aligned. That is, the parallel inspection light beams are made incident on all the non-through holes 21 and the through holes 20 drilled in the work 1, and the inspection process is completed by the glance of the inspector. . Of course, if the ground glass F is installed between the inspection light source and the work 1, the inspection light source does not have to be the fluorescent lamp FL, and may be a point light source or the like.

Further, in the above-described first embodiment and this modification, a further modification in which the naked eye E of the inspector is replaced by an optical sensor system to automate the inspection process is possible. This optical sensor system does not perform feedback control of the laser processing machine but merely discriminates lightness from darkness in the inspection process, and therefore does not result in a large capital investment cost. Further, as the optical sensor, a linearly arranged CCD, a CCD in which a large number of pixels are arranged in a plane, or the like appropriately selected from various kinds of optical sensors may be used. In such a modified mode in which the inspection process is automated, there is an effect that the facility cost is also reduced although some facility investment cost is required.

(Variation 2 of Embodiment 1) As Variation 2 of this embodiment, as shown in FIG. 4, the perforation step is a step of perforating the work 1 with a laser beam, and the inspection step is performed by this laser beam. It is possible to carry out the method of inspecting the depth of the non-through hole, which is a step of detecting whether or not the inspection portion C of the work 1 is penetrated.

In this modification, laser drilling is performed on the inspection portion C of the work 1 in the drilling step, as in the first embodiment. On the other hand, unlike the above-described first embodiment, it is a feature of the present modified embodiment that an inspection step of detecting whether or not the laser beam penetrates the inspection portion C is performed in parallel with the perforation step.

If the laser beam applied to the work 1 from the laser processing machine penetrates the work 1,
The light is obliquely incident on the optical glass G which is on the extension of the axis of the laser processing machine and is arranged on the back surface 1b side of the work 1.
Optical glass is a thin flat glass with high transparency,
It is fixed so that the laser beam is incident at 45 °. When the laser beam enters the optical glass, most of the laser beam passes through the optical glass, and only a part of the laser beam is reflected and enters the optical sensor device S.

Here, in the apparatus configuration of this modification, the positions and orientations of the laser processing machine, the optical glass G, and the optical sensor device S must be precisely determined with respect to each other, so these are fixed to the bed. There is. Then, a moving device (not shown) is designed so that the work 1 is automatically and sequentially moved so that a portion of the surface 1a of the work 1 to be perforated comes to a position where it is hit by a laser beam.

The optical sensor device S further attenuates the incident laser beam through frosted glass, an optical filter, etc., and then receives it with a built-in optical sensor. When the received light level exceeds a predetermined threshold value, the laser beam is detected. It emits a signal. Therefore, the tip of the non-through hole 21 is close to the back surface 1b, 1b ', 1b "of the work 1, and the light sensor device S does not emit a light reception signal when the transmitted light slightly leaks. The light receiving signal is emitted from the optical sensor only when the through hole 20 is opened in the work 1 during laser perforation.

In other words, if a light reception signal is output from the optical sensor S during punching of the processed portion B, it means that the through hole 20 has been opened in the processed portion B. At that stage, therefore, the work 1 is a defective product. It is judged and removed from the processing line. Similarly, if a light reception signal is output from the optical sensor S during drilling in the second inspection part C2, the through hole 20 is opened in the second inspection part C2, and the drilling depth in the processed part B is too deep. Therefore, the work 1 is judged to be defective at that stage and is removed from the processing line. On the contrary, in the first inspection part C1, an arbitrary through hole 2
If the received light signal is not output from the optical sensor device S even when the drilling of 0 is completed, it is considered that the drilling depth in the processing portion B was insufficient, and the work 1 is considered as a defective product.

That is, in this modification, it is not necessary to separately perform the inspection step after the punching step, and the man-hours are reduced accordingly. Not only that, even during the perforation process of the processing section B or the second inspection section C2, a defective product can be found and removed from the processing line during the perforation process. It is not necessary to continue the drilling process, and the number of steps is further reduced.

Therefore, according to this modification, in addition to the four effects of the first embodiment described above, the number of man-hours is reduced as a whole of the punching process and the inspection process which are carried out in parallel.
This has the effect that the drilling process and its inspection proceed faster.

If the state of the laser processing machine can be kept constant and the output of the laser beam is sufficiently stable, the first inspection section C1, the second inspection section C2, and the processing section B are lasered in this order. It does not matter if it is perforated. In this case, since the inspection unit C is inspected while being laser-drilled prior to the processing unit B, it is possible to determine defective products at an early stage and further reduce the waste of the process.

(Modification 3 of Embodiment 1) As modification 3 of this embodiment, the depth of the non-penetrating hole in which the front and back of the work 1 are reversed in Embodiment 1 and its modifications 1 and 2 is described above. The inspection method can also be implemented. Then,
There is a step of the inspection part C on the surface where the laser drilling is performed,
The perforation step and the inspection step are performed with the back surface flush.

In this modification, a large number of openings are hidden as a back surface in the product state in which the surface of the non-through holes 21 and the through holes 20 at the root of the opening has a base opening, and in the product state the surface is in the punching step. You can bring the stepless backside. As a result, a product having a flush surface can be produced if the small several openings formed by the through holes 20 of the first inspection part C1 do not cause inconvenience in terms of appearance and function. Of course, if the through hole 20 of the first inspection part C1 is inconvenient, only the first inspection part C1 may be separated from the work 1.

(Modification 4 of Embodiment 1) As Modification 4 of the present embodiment, in the above-described Embodiment 1, its Modification 1 or Modification 3, the work 1 is composed of the punching step and the inspection step.
It is also possible to carry out the method for inspecting the depth of a non-through hole in which the front and back are reversed. Also in this modification, since the light of the fluorescent lamp FL passing through the through hole 20 can be detected, there is no particular inconvenience, and the same operation and effect as those of the above-described first embodiment can be obtained.

[Embodiment 2] (Structure of Embodiment 2) As Embodiment 2 of the present invention, as shown in FIG. 5, the depth of the non-penetrating hole is characterized in that the work 1 has an inclination inspection portion C ′. The inspection method can be carried out. Here, the work 1 is, as an inspection unit adjacent to the processing unit B, an inclination inspection unit C ′ whose thickness continuously changes within a range that covers the allowable range Tt of the predetermined depth of the non-through hole 21.
With. Then, the perforation step is a step of perforating a plurality of portions of the inclination inspection part C ′ having different thicknesses.

That is, in the present embodiment, the shape of the work 1 is different from that of the first embodiment, and the end of the processed portion B having the plate thickness T0 has a sloped surface whose thickness continuously changes from T0 to T3. The inclination inspection part C ′ on which the back surface 1c is formed continues. Here, the maximum plate thickness T0 and the minimum plate thickness T of the inclination inspection part C '
3 and the permissible minimum value T1 and the maximum permissible value T2 of the perforation depth of the non-through hole 21 are T3 <T1 <T2 <T0.

Then, a portion having a plate thickness corresponding to the permissible range of the perforation depth of the non-through hole 21 or the management width Tt is formed with the permissible range Ct of a predetermined width in the vicinity of the central portion of the inclination inspection part C ′. is doing. From this, it is clear that the plate thickness at the inclination inspection portion C ′ continuously changes within a range that covers the allowable range Tt of the predetermined depth of the non-through hole 21. .

(Effects of Embodiment 2) In this embodiment, the inclination inspection portion C'is a flat slope whose thickness continuously changes within a range that covers the allowable range Tt of the depth of the non-penetrating hole 21. In the boring step, a large number of holes are bored along the inclination direction. Then, if the thickness of the inclined inspection portion C ′ is inspected, the depth of the non-through holes 21 formed in the processed portion B can be estimated in a fairly fine and stepwise manner. it can.

That is, the thickness of the inclination inspection portion C'is the thickness T0 which exceeds the maximum permissible value T2 of the perforation depth of the non-through hole 21 by a predetermined amount, and the thickness T3 which is lower than the minimum allowable value T1 by a predetermined amount. The taper is formed by continuously forming a flat slope. In the perforation step, since a large number of holes are perforated in this range at equal intervals, in the inspection step, at which portion of the inclination inspection part C ′ the transition from the non-through hole 21 to the through hole 20 is made. Is inspected. Then, the inclination inspection unit C '
The thickness of the portion of the non-through hole 21 that transitions from the non-through hole 21 is regarded as the depth of the non-through hole 21 formed in the processed portion B, and the depth of the non-through hole 21 is relatively accurately determined. It is possible to estimate.

The inspection result in the inspection step cannot be applied to the work 1 since the processed portion B has already been perforated in the perforation step. However, since it is known how much the depth of the next work 1 should be adjusted, the depth of the non-through holes 21 of the next work 1 can be adjusted to a more appropriate degree.

Here, if the transition position from the non-through hole 21 to the through hole 20 is within the allowable range Ct of the predetermined width in the inclination inspection portion C ′, the non-through hole 21 is drilled in the processed portion B as well. The depth is estimated to be within the allowable range Tt. Furthermore, if this transition position is in the center of the allowable range Ct, the perforation depth of the non-through holes 21 is in the middle of the allowable minimum value T1 and the allowable maximum value T2, and it can be said that this is the most preferable state. . On the contrary, if this transition position is out of the center of the allowable range Ct, it is clear how much the depth of the non-penetrating hole 21 should be adjusted by observing in which direction and how much. become.

The variation in the depth of the non-penetrating holes 21 is more than the difference in the thickness of the inclination inspection portion C'generated between the holes adjacent to each other formed in the inclination inspection portion C'at a predetermined pitch. When the value is large, the transition from the non-through hole 21 to the through hole 20 may occur back and forth gradually. In such a case, it is difficult to specify the transition position in one place, and there is no choice but to specify the transition position with a certain width. However, if the transition position having the width is within the allowable range Ct, it is estimated that the drilling depth of the non-through hole 21 is also within the desired allowable range or the management width Tt.

Therefore, according to the present embodiment, in addition to the four effects of the first embodiment described above, it becomes possible to accurately estimate the drilling depth of the non-through hole 21 formed in the processed portion B, As a result, there is an effect that the perforation depth in the perforation step can be appropriately adjusted.

(Various Modifications of Embodiment 2) Various modifications corresponding to Modifications 1 to 4 of Embodiment 1 described above are also applied to the depth inspection method for non-through holes of this embodiment. Can be performed, and the action and effect peculiar to each modification can be obtained.

Further, it is possible to carry out a modified mode in which, in the punching step, punching is performed along an oblique direction having a predetermined angle with respect to the tilt direction of the tilt inspection section C '. According to this modification, the difference in plate thickness between the positions of holes that are adjacent to each other becomes small, and it becomes possible to more accurately measure the depth of perforation. That is, even if the width of the inclination inspection unit C ′ is not increased to reduce the inclination, the same effect can be obtained without increasing the width of the inclination inspection unit C ′.

[Embodiment 3] (Structure and operation of Embodiment 3) As Embodiment 3 of the present invention, as shown in FIG. 6, a work 1 is a non-penetrating work in which a lid plate of a portion for accommodating an airbag of an automobile is used. It is also possible to carry out a method for inspecting the depth of holes. The work 1 has a first inspection portion C1 having a plate thickness T1 corresponding to an allowable minimum value of the perforation depth of the non-through hole 21 in the central portion of the processing portion B where the non-through hole 21 is to be perforated.

That is, the work 1 has a predetermined inner diameter for the purpose of forming an H-shaped fragile portion so that when the air bag is deployed, the door opens up and down to form a substantially rectangular break. The non-through holes 21 are arranged in an H shape at a predetermined pitch. Therefore, a pair of left and right non-through holes 21 is formed in the vertical direction (a direction perpendicular to the paper surface of FIG. 6) from the left and right non-through holes 21 in FIG. A first inspection portion C1 having a predetermined width and a thin plate thickness is formed in the center of the illustrated processing portion B of the workpiece 1 which is perforated horizontally. On the other hand, unlike the first embodiment, the second inspection portion C2 is not formed in the work 1 of the present embodiment.

Here, the first inspection portion C1 having the thinnest plate thickness is arranged at the central portion of the pair of processed portions B on both the left and right sides because the inflation force is generated when the airbag is deployed, It is intended that the fracture starts to open from the central portion of the processed portion B.

Incidentally, in the punching step, the back surface 1 of the first inspection portion C1 is
Although a plurality of through holes 20 are opened in b ′, a decorative plate such as a logo made of soft resin is attached to the back surface 1b ′ of the first inspection portion C1 after the inspection process is completed.
The decorative plate is attached in order to prevent the occupant from seeing the through holes 20 in a product state and improve the aesthetic appearance. In addition, the soft resin is used as the material of the decorative plate so that the occupant will not be injured even if the decorative plate that is torn when the airbag is deployed touches the occupant.

In the preliminary step, the work 1 is formed into the above-mentioned predetermined shape. The material forming work 1 is
It is a black polypropylene-based thermoplastic resin as in Example 1 described above. The shape of the work 1 is a plate material having a substantially constant thickness except for the first inspection portion C1 and forming a very gentle quadric surface that is convex toward the back surface 1b. In the state where the work 1 is a lid plate as a product, the front surface 1a in the perforation step in which the non-through holes 21 are also opened is the back side, while the back surface 1b in the perforation step is the front side visible to the occupant. Become.

Therefore, the back surface 1b of the work 1 is provided with unevenness as a grain which has a leather-like appearance. On the other hand, the surface 1a of the work 1 is smooth. The plate thickness T0 of the work 1 is from the front surface 1a to the surface of the average height of the irregularities on the back surface 1b.

Next, in the perforation step, laser perforation is performed by the laser processing machine as in the first embodiment. On this occasion,
It is desirable that the non-through holes 21 reach very close to the back surface 1b so that the work 1 can easily break when the airbag is deployed. On the other hand, when the work 1 is a product and is installed as a cover plate for an airbag, the occupant can see the opening, which spoils the appearance. Therefore, it is desirable that the tip of the non-through hole 21 is set appropriately close to the back surface 1b within a range that does not reach the back surface 1b.

Specifically, the perforation depth of the non-through holes 21 is
The average value is designed to be 0.35 mm smaller than the plate thickness T0, and an allowable range of ± 0.20 mm is provided above and below the average value. That is, the permissible maximum value T2 of the perforation depth of the non-through holes 21 is 0.15 than the plate thickness T0 of the work 1.
The allowable minimum value T1 is smaller than the plate thickness T0 of the work 1 by 0.55 mm. Therefore, the permissible range of the perforation depth of the non-through holes 21 or the management width Tt is 0.4 mm.

The above-mentioned allowable range of ± 0.20 mm is due to variations in the base material characteristics of the work 1 that occur during molding.
It is a design value determined in consideration of the accuracy limit (about ± 0.1 mm) of the laser processing machine and the texture roughness of the back surface 1b of the work 1.

In the punching step, each non-through hole 21 is
The inner diameter is only 0.2 mm, but the surface 1a
Only the opening is formed so as to have an inner diameter of about 0.3 mm. Since the pitch of the non-through holes 21 is 0.5 mm, the distance between the non-through holes 21 adjacent to each other is slightly less than 0.
Only 3 mm apart. Of course, since the first inspection portion C1 is also laser-drilled under the same conditions as the processing portion B, a large number of through holes 20 having the same inner diameter and pitch as the non-through holes 21 except that they are penetrated are The inspection portion C1 is formed.

Here, in the needle punching introduced in the section of the prior art, even if the inner diameter of the non-through hole 21 can be made small, it is 0.5.
Since the size is only mm, the thinner non-through holes 21 can be formed more densely in the present embodiment in which the laser processing is performed in the punching step. Therefore, the thickness between the non-through hole 21 and the through hole 20 which are naturally adjacent to each other is reduced, and
The fragments that scatter when a fracture occurs are smaller, and the jagged edges are smaller, making it less likely to damage the occupant. Further, in the present embodiment, unlike needle perforation, resin swelling does not occur at the root openings of the non-through holes 21 and the through holes 20, and thus this swelling is scattered and scattered into the eyes of the occupant. There is no inconvenience to enter.

Finally, in the inspection step, as shown in FIG. 3 as well, three fluorescent lamps are used as the inspection light source and the through-hole 2 is used.
0 and the non-through hole 21 are visually inspected.

That is, as in the first embodiment, in addition to the fluorescent lamp FL, which horizontally radiates light toward the inside of the non-through hole 21 of the processed portion B and the through hole 20 of the first inspection portion C1, Two fluorescent lamps FL1 and FL2 are vertically arranged and used.
These two fluorescent lamps FL1 and FL2 emit light inside the non-through holes 21 formed in the processing parts (not shown) arranged along the vertical lines on both sides of the fragile part formed in the H shape. It is a light source for inspection that irradiates. These three fluorescent lamps FL, FL
1 and FL2 are arranged so as to irradiate the inside of all through holes 20 and non-through holes 21 from the surface 1a side of the work 1.

On the other hand, the ground glass F is disposed in the vicinity of the back surface 1b of the work 1, and the inspector visually confirms the bright spot P with the naked eye E from behind the ground glass F to form the through hole 20. The inspection of the designated position is performed.

That is, in the frosted glass F, the bright spots P having the same size and brightness are arranged at equal intervals only in the portion behind the first inspection portion C1, and the bright spots P are arranged in other portions. If not visible, the inspection for laser drilling passes.

On the other hand, if there is a lack of the bright spot P in the portion corresponding to the first inspection portion C1, it is presumed that the depth of the non-penetrating hole 21 is insufficient in most cases, so the inspection result is unacceptable. Will be On the contrary, if the bright spot P is recognized in a portion other than the portion corresponding to the first inspection portion C1, it is estimated that the non-through hole 21 is too deep in most cases and the weak portion is lacking in strength. The test result will fail.

However, the number of through holes formed in the processed portion B is small, the openings are fine, and the appearance is not affected.
If it can withstand an appropriate strength test, it may overturn the inspection result in the inspection process. Where to draw the pass / fail border line on this side will be a design matter that is somewhat different depending on the manufacturer's concept of quality control.

(Effect of Embodiment 3) In this embodiment, as described above, there is only the first inspection portion C1 having a thickness corresponding to the permissible minimum value T1 of the perforation depth of the non-through hole 21, and the processing portion B is present. Is thicker than the permissible maximum value T2 of the drilling depth. Therefore, by optically inspecting the first inspection portion C1, all the through holes 2
It is confirmed that 0 properly penetrates the first inspection portion C1 of the work 1. Further, if it is confirmed that the through hole 20 does not exist in the processed portion B by performing the optical inspection on all the perforated portions of the processed portion B, all the holes formed in the processed portion B are the non-through holes 21. Is guaranteed to be

As a result, almost the same effects as the four effects of the first embodiment described above are obtained, and the following effects peculiar to the present embodiment are obtained.

First, of the H-shaped fragile portion that causes a breakage when the airbag is activated, the through hole 20 is formed just in the center.
Since there is the first inspection portion C1 having a thinner plate thickness than the other portions, the rupture starts from the central portion of the fragile portion where the first inspection portion C1 is located. As a result, in the work 1 that has become a product (airbag cover plate), the rupture that has occurred from the central portion spreads out in a substantially symmetrical manner to the left and right, and there is an effect that a smooth and smooth opening can be obtained. .

Second, the laser-pierced non-through hole 21.
Further, the through holes 20 are very thin, and the arrangement pitch is also finely formed. Therefore, the fragments generated from the breakage of the work 1 when the airbag is activated are extremely small and very small, and the jaggedness of the breakage is very small, so that the occupant is better prevented from being scattered due to the scattering of the fragments or the contact of the breakage. There is an effect that is done.

(Various Modifications of Third Embodiment) Various modifications corresponding to the first modification to the fourth modification of the first embodiment are also applied to the depth inspection method for the non-through holes according to the present embodiment. Can be performed, and the action and effect peculiar to each modification can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a punching process of Example 1.

FIG. 2 is a schematic sectional view showing an inspection process of Example 1.

FIG. 3 is a schematic cross-sectional view showing an inspection process of modification 1 of example 1.

FIG. 4 is a schematic cross-sectional view showing the perforation inspection method according to the second modification of the first embodiment.

FIG. 5 is a schematic cross-sectional view showing the inspection process of Example 2

FIG. 6 is a schematic cross-sectional view showing the inspection process of Example 3

FIG. 7 is a schematic diagram showing a method for detecting the depth of perforation according to Prior Art 1.

[Explanation of symbols]

1: Workpiece (workpiece in which a non-through hole is formed) 1a: Front surface (front surface in a punching process and is not related to front and back as a product) 1b: Back surface (back surface in a drilling process and front and back as a product) 1b ': the back surface 1b "of the first inspection part: the back surface 1c of the second inspection part: the inclined back surface 20 of the tilt inspection part 20: through hole 21: non-through hole B: processed part (drilled in the work) Part) C: Inspection part (portion of work to be inspected after drilling) C1: First inspection part (thickness part corresponding to the allowable minimum value of non-through hole depth) C1: Second inspection part (non-through hole) C ': Inclination inspection part (covers the permissible range of non-through hole depth) Ct: Inclination inspection part's allowable range T0: Machined part thickness T1: First inspection Part thickness (corresponding to the allowable minimum depth of the non-through hole) T2: Plate thickness of the second inspection part (non-penetrating part) Corresponds to the hole depth of the allowable maximum value) T3: the end thickness of the inclined inspection section (T3 <T1 <T2 <T
0) Tt: Permissible range of non-through hole depth (perforation depth control width, T
t = T2-T1) E: naked eye of inspector F: ground glass FL, FL1, FL2: straight rod-shaped fluorescent lamp (light source for inspection) G: optical glass P: bright spot S: optical sensor device

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2F065 AA25 BB05 FF44 GG03 GG04                       GG12 GG16 JJ02 JJ03 JJ25                       JJ26                 2G051 AA32 BA01 CA11 CB02 CB05                       DA06 DA13                 4E068 AF01 CB08 CC01

Claims (5)

[Claims] 1. A drilling step for forming a non-through hole from a surface of a workpiece to a predetermined depth inside the workpiece, and one of a surface of the workpiece and a back surface facing the surface. A method of inspecting the depth of this hole by irradiating light toward the other side and observing light leaking from the other side, and An inspection area having a predetermined thickness equal to or less than the thickness of the perforated portion of the hole, and a test piece made of the same material as the work and having a predetermined thickness that is at least partially thinner than the perforated portion of the non-through hole. Of these, at least one further has a preliminary step of providing an inspection unit, the perforation step is a step of perforating the inspection unit under the same conditions as the processing unit, the inspection step, the preliminary step Then, from the one side of the inspection unit A method of inspecting the depth of a non-through hole, which comprises a step of observing the light leaked to the other side and determining the length of the depth of the non-through hole in the processed portion and the thickness of the inspection portion. . 2. The inspection unit comprises a first inspection unit having a thickness corresponding to an allowable minimum value of the predetermined depth of the non-through hole and an allowable maximum value of the predetermined depth of the non-through hole. The non-through hole depth inspection method according to claim 1, wherein at least one of the second inspection portion having a corresponding thickness is provided. 3. The inspecting unit is an inclination inspecting unit whose thickness continuously or stepwise changes within a range that covers an allowable range of the predetermined depth of the non-through hole. The depth inspection method for a non-penetrating hole according to claim 1, which is a step of boring a plurality of portions of the inclination inspection portion having different thicknesses. 4. The punching step is a step of punching the work with a laser beam, and the inspecting step is a step of detecting whether or not the laser beam penetrates the inspection portion of the work. 1. The depth inspection method for a non-through hole according to 1. 5. In the inspecting step, the light leaked from the inspecting unit is received by a scattering means which is one of a scattering semi-transparent body and a diffuse reflection surface, and scattered by the scattering means. The depth inspection method for a non-through hole according to claim 1, which is a step of detecting light.