JPH0611318A - Method for inspecting quality of molded goods by metallic mold and quality inspecting device using it - Google Patents

Abstract

PURPOSE:To obtain a quality inspecting method and device by which the quality of molded goods of plastics molding or metallic mold pressing can be accurately discriminated. CONSTITUTION:By irradiating a mobile or fixed metallic mold 1 or 2 to which molded goods to be inspected are stuck with light from a point light source 4 from a prescribed oblique direction against the relatively moving direction between the molds 1 and 2, the picture of the moving locus of the light source 4 formed along the shape of the molded goods as the molded goods move is taken at the time of opening the mold. Then, by comparing and collating the picture data of the moving locus with the picture data of a predetermined reference moving locus, the quality of the molded goods is discriminated based on the coincidence between the loci within a predetermined condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quality inspection device for molded products in plastic molding and die pressing.

[0002]

2. Description of the Related Art Conventionally, as this type of quality inspection apparatus,
For example, as in Japanese Patent Application No. 2-225496, by illuminating a mold with slit light and analyzing a slit pattern that changes according to the shape of the molded product, the quality of the molded product can be judged, It is known that, as in Japanese Patent Laid-Open No. 3-126428, the quality of a molded product is judged by irradiating a mold with light and analyzing a change in luminance according to the shape of the molded product.

[0003]

However, in such a conventional quality inspection apparatus, the molded product is present at the timing before the mold is opened and the molded product is taken out, that is, in the movable mold. In the case of quality inspection in a state where the movable mold comes to a predetermined position, an image is picked up by an image pickup device such as a video camera, and the image data obtained by this is signal-processed. However, due to the mechanical precision of the drive mechanism of the movable mold, it is extremely difficult to capture an image in synchronization with the movable mold when it comes to a predetermined position, and it is always possible to obtain it under the same conditions. Since the obtained image data is not analyzed, the inspection accuracy is deteriorated.

Further, in the quality inspection apparatus of Japanese Patent Application No. 2-225496, it is extremely difficult to realize highly accurate slit light, and there is a problem that a large projector is required, for example. there were. In addition, Japanese Patent Application No. 3-1
In the quality inspection device of No. 26428, there is a change in brightness due to indoor lighting at the place where the quality inspection device is installed,
There is a problem that the inspection accuracy varies due to the difference in the material of the molded product, for example, the change in color of the plastic resin or the iron plate.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a quality inspection device for accurately inspecting a defective appearance or the like of a molded product by die molding. .

[0006]

In order to achieve such an object, the present invention is directed to a movable mold or a fixed mold to which a molded product to be inspected is attached, and the movable mold and the fixed mold. Irradiate a point light source from a predetermined oblique direction relative to the relative movement direction, and image the movement trajectory of the point light source along the shape of the molded product along with the movement of the molded product due to mold opening, and obtain the image data of the movement trajectory. By comparing and collating with the image data of a predetermined reference movement locus, it is decided to judge the quality of the quality based on the agreement within the predetermined conditions.

[0007]

According to the quality inspection apparatus having such a structure, the point light source performs point scanning on the molded product as the molded product attached to the movable mold or the fixed mold moves by opening the mold, and the point scanning is performed. The movement locus that appears in the figure represents the actual shape of the molded product, and by comparing and collating the image data of this movement locus with a predetermined movement locus, it is possible to judge not only the quality of the molded product but also the defective part. Become.

Especially, if the inspection object is set in advance within the angle of view of the image pickup camera so that the whole inspection object can be accommodated, even if the image is picked up at a relatively non-rigid timing, the die and the molded product are inspected. Since the target range is determined, strict position control of the mold as in the past is unnecessary. Further, since the trajectory of the point light source is recognized, the shape can be determined by a simple binarization process, and the inspection accuracy does not change due to external factors such as external illumination.

Further, since the point light source can be easily realized by laser light or a relatively simple optical system, it is possible to provide a quality inspection apparatus which is more applicable than the prior art which applies slit light.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, the overall configuration of the inspection device will be described with reference to FIG. It is applied to plastic injection molding and iron plate press molding machines. 1 is the movable mold of these molding machines,
Reference numeral 2 denotes a fixed-side mold. In a plastic injection molding machine, for example, in a state where the movable-side mold 1 is fitted to the fixed-side mold 2, a plastic resin is injected and solidified, and then the movable-side mold 1 is After performing the mold opening operation for removing, the molded product 3 is separated from the movable side mold 1, and the movable side mold 1 is fixed again to the fixed side mold 2.
Repeat the same process according to. Further, when the mold is opened, the movable mold 1 moves in parallel while always facing the fixed mold 2.

Reference numeral 4 denotes a point light source of the inspection device, which is a movable mold 1.
Illuminates the passing light of the movable die 1 from the oblique direction of a predetermined angle θ with respect to the moving direction X of the movable mold 1. The point light source 4 is fixed to the inspection device and is always stationary. Reference numeral 5 denotes a video camera for picking up an image of the inside of the movable-side mold 1, and even if the movable-side mold 1 moves back and forth with respect to the fixed-side mold 2, it can be moved within a predetermined angle range The angle of view is set so that the image of the molded product 3 attached to the side mold 1 is included.

According to this structure, when the movable mold 1 moves so as to gradually separate from the fixed mold 2 during the mold,
The light from the point light source 4 starts to hit the inner end of the movable side mold 1 from a predetermined point x1 where the movable side mold 1 is close to the fixed side mold 2, and the irradiation portion moves as the movable side mold 1 gradually moves away. The inner surface of the side die 1 is moved while scanning from top to bottom.
In the embodiment, the point light source 4 is installed at a position vertically above the moving direction of the movable mold 1 in order to perform this scanning only in the vertical direction.

As a result, as shown in FIG. 2, when a portion of the molded product 3 attached to the inside of the movable mold 1 when the mold is opened is vertically scanned, a point corresponding to the shape of the molded product 3 is obtained. The trajectory pattern of the light source is captured by the video camera 5. Next, the image signal of the trajectory pattern of the point light source captured by the video camera 5 is processed by the signal processing unit having the configuration shown in FIG. That is, the analog image signal input by the video camera 5 for each imaging period is an 8-bit digital signal for each pixel based on the dot sequential scanning of the video camera 5 in the A / D converter 7a in the binarization processing unit 7. Is converted into binary digital data of logical values "1" and "0" by the comparator 7b comparing with a preset threshold value Vth. And
The binary digital data for each pixel is stored in the image storage memory 8a in the image processing unit 8 in synchronization with the timing of the dot sequential scanning. Therefore, the shape of the locus pattern formed by the point light source 4 is stored in the image storage memory 8a as binary data without breaking the shape.

Here, the threshold value Vt of the comparator 7b
h is input by manual scanning from a keyboard or the like described later, or the image processing device 8 temporarily stores all image data from the A / D converter 6 in another image storage memory 8b, The threshold value Vth calculated so as to divide the upper N% is set by automatic adjustment, and this manual input and automatic adjustment can be performed by command designation from the keyboard.

Further, in order to digitize the digital signal output from the A / D converter 7a, software of the image processing device 8 may be used instead of the comparator 7b. Further, the image processing device 8 has a built-in image data storage unit 8c for storing the data of the binary pattern of the trajectory pattern which is a reference in advance.

Reference numeral 9 denotes an interface that is connected to a control unit (not shown) of the molding machine to send and receive an inspection start signal and a signal of a judgment result of quality inspection, and the moving operation of the movable mold 1 and the inspection. The purpose is to synchronize processing with the start, and to automate processing such as stopping the molding operation in response to a result of determination such as poor quality. Reference numeral 10 denotes an interface for connecting input / output devices such as the keyboard and printer to the image processing apparatus 8 to input various commands and print inspection results.

Next, the processing operation of the quality inspection apparatus having the above configuration will be described with reference to the flowchart of FIG. First, before starting the actual inspection, an initialization process for creating the reference trajectory pattern, setting the threshold value Vth of the comparator 7b, and setting the inspection area is performed.

That is, in step S1, a normal molding operation is performed, and when the movable mold 1 moves when the mold is opened, a dot pattern locus formed on the molded product 3 by the point light source 4 is imaged by the video camera 5. . Then, each pixel is digitized by the A / D converter 7a and stored in the image data storage memory 8b in the image processing device 8, and the calculation unit stores the upper N bits of all image data.
The threshold value Vth calculated so as to divide% is automatically determined, and this value Vth is set as the threshold value of the comparator 7b.

Further, the calculation unit is the image data storage memory 8
By comparing the image data of each pixel of b with the threshold value Vth and setting the pixel having a value larger than the threshold value Vth to the logical value “1” and the pixel having a smaller value to the logical value “0”, the point light source The dot pattern formed by the irradiation of 4 is obtained as the logical value "1". Next, in step S2, the barycentric coordinates of the dot pattern are obtained, and the locus formed by connecting these barycentric coordinates is stored in the image data storage memory 8c as reference locus pattern data.

Next, the scanner determines the inspection range while observing the image of the opened mold on the monitor, and instructs the coordinates of the inspection range to the arithmetic unit of the image processing device 8 using a keyboard or the like. In this way, by performing the processing of steps S1 to S3, predetermined data regarding a non-defective molded product is set in advance.

Next, the actual inspection is started. First, in step S4, in synchronization with the input of a molding start signal from the molding machine via the molding machine interface 9,
The inspection process is started and the point light source 4 emits light and the video camera 5
The image data captured when the movable mold 1 is opened is converted into binary logical image data by the A / D converter 7a and the comparator 7b.

Next, the barycentric coordinates of the dot pattern are calculated in step S5, and the process is repeated until it is confirmed in step S6 that the moving operation of the movable mold 1 at the time of mold opening is completed. Therefore, the barycentric coordinates of each of the plurality of dot patterns as shown in FIG. 2 are obtained. Next, in step S7, data indicating the locus pattern of the dot pattern 6 is created by connecting the respective barycentric coordinates in time series, and stored in the memory 8a.

Next, in steps S8 and S9, the reference locus pattern data stored in advance in the image storage memory 8c and the locus pattern data in the memory 8a obtained at the time of inspection are compared and collated. , Judgment of mutual agreement, and if there is agreement above a predetermined standard,
It is determined that the molded product is normal. Further, the process of matching judgment will be described with reference to FIG.
C is a bent line having no line width on the virtual coordinates, and the reference area AC is determined by providing a constant width for this trajectory pattern LC.

Next, the locus pattern L obtained by the inspection
Similarly, for A, an area AR having a constant width is set. Then, the number of pixels Ni included in the area E where both areas AC and AR overlap is obtained, and compared with a value Nth set in advance as a quality acceptance criterion. If Ni ≧ Nth, an acceptable product,
When Ni <Nth, it is determined that the product is rejected. Then, the determination result is notified by being transferred to an alarm buzzer or the like via the user interface 10, and is also transferred to the molding machine via the molding machine interface 9.

Thus, the processing of steps S4 to S9 is
The quality of the molded product can be continuously determined by synchronizing with the operation from one molding to the mold opening and repeating the same processing at the next molding. In this embodiment, since the single point light source 4 irradiates the movable mold 1, the inspection of only a minute portion is realized.
When inspecting multiple parts of a molded product, multiple point light sources 4
Can be realized by arranging in parallel and comparing and collating the trajectory pattern by each point light source 4 with a plurality of preset reference trajectory patterns.

Next, another embodiment will be described with reference to FIG.
This shows a quality inspection device applied to a molding machine having a structure in which a molded product adheres to a fixed-side mold when the mold is opened. That is, the point light source 4 is fixed to the movable side mold 1 or a member that moves integrally with the movable side mold, and the point light source 4 irradiates the molded product 3 with the movement of the movable side mold 1 when the mold is opened. The irradiation angle of the point light source 4 is set so that the position gradually shifts. Further, the video camera 5 is directed to the inside of the fixed-side mold 2 and images the dot pattern trajectory pattern formed by the change of the irradiation position.

Then, the quality of the quality is judged by similarly analyzing the image of the locus pattern obtained by the image pickup by the image processing means shown in FIG. According to this embodiment, the point light source 4 is moved by the relative movement of the movable mold 1 and the fixed mold 2 to scan the molded product 3. Therefore, the same principle as in the first embodiment is used. It is possible to judge the quality of the molded product.

Next, still another embodiment will be described with reference to FIG. In FIG. 7, the same or corresponding parts as in FIG. 3 are indicated by the same reference numerals. This embodiment is a quality inspection device that makes a quality decision on the quality of a dot pattern collectively captured by a video camera 5 by irradiating a point light source 4 (see FIG. 1). That is, the electronic shutter 11 whose opening and closing is controlled by the image processing device 8 is installed in front of the video camera 5. The electronic shutter 11 is normally closed and is opened only during the period when each mold is opened in synchronization with the timing of the inspection start. Therefore, the point light source 4 is continuously opened during the scanning of the molded product, and is closed during the operation other than the mold opening.

Further, the video camera 5 operates in the still image mode during each mold opening period and picks up one frame image during the mold opening period. Therefore, while the electronic shutter 11 is open, the video camera 5 adjusts the brightness of the dot pattern, and when the electronic shutter 11 is closed, the image signal of one frame image is processed by the binarization processing unit 7 for each pixel. Logical value "1"
Alternatively, it is converted into image data of “0” and stored in the memory in the image processing unit 8.

Then, by performing the same image processing as that of the first embodiment on the binarized image data,
The quality of the molded product is determined by creating dot pattern locus pattern data and comparing and collating with the data of a predetermined standard locus pattern during normal operation. According to this embodiment, the fact that the image pickup device of the video camera 5 has a function of integrating photocharges is used, and the quality inspection is realized only by analyzing the trajectory pattern obtained from one frame image. The timing control of can be simplified.

[0031]

As described above, according to the present invention, the movable mold or the fixed mold to which the molded product to be inspected adheres is predetermined from the relative moving direction of the movable mold and the fixed mold. Illuminating the point light source from the oblique direction, and imaging the movement trajectory of the point light source along the shape of the molded product along with the movement of the molded product due to mold opening, and the image data of the movement trajectory is determined by a predetermined reference. Since it was decided to compare and collate with the image data of the movement locus of, and to judge the quality of the image based on the agreement within the predetermined conditions, the entire inspection target is within the angle of view of the imaging camera for imaging. If you set it in advance so that it will fit, the inspection target range of the mold and the molded product will be determined even if you perform imaging with relatively less precise timing, so strict position control of the mold as in the past is not necessary. Become.

Further, since the locus by the point light source is recognized,
The shape can be determined by a simple binarization process, and the inspection accuracy does not change due to external factors such as external illumination. Further, since the point light source can be easily realized by a laser beam or a relatively simple optical system, it is possible to provide a quality inspection device having higher applicability and accuracy as compared with the conventional technique using slit light.

[Brief description of drawings]

FIG. 1 is a configuration explanatory view showing a configuration of an embodiment of a quality inspection device according to the present invention.

FIG. 2 is an explanatory diagram showing an example of an image captured by a camera.

FIG. 3 is an explanatory diagram illustrating a configuration of an image processing unit according to an embodiment.

FIG. 4 is a flowchart for explaining the operation of the embodiment.

FIG. 5 is an explanatory diagram for explaining the non-defective product determination principle of the embodiment.

FIG. 6 is a structural explanatory view showing the structure of another embodiment of the present invention.

FIG. 7 is a configuration explanatory view showing a configuration of still another embodiment of the present invention.

[Explanation of symbols]

 1 ... Movable mold 2 ... Fixed mold 3 ... Molded product 4 ... Point light source 5 ... Camera 6 ... Point pattern 7 ... Binarization device 7a ... A / D converter 7b ... Comparator Lator 8 …… Image processing device 9 …… Molding machine interface 10 …… User interface 11 …… Electronic shutter

Claims (4)

[Claims] 1. A method for inspecting the quality of a molded product in a mold of a mold molding machine, wherein the mold is irradiated with point-shaped light having a size in a normal state, and the point-shaped light is used to irradiate the point-shaped light. While imaging the pattern that appears in the mold and converting it to a video signal,
Converting the video signal into binary image data for each pixel,
Based on the data obtained by obtaining the locus from the binarized data continuously input while the mold is moving, the point-shaped light having a size inside the mold is used during the mold molding process. Is irradiated, the pattern appearing in the mold by the point light is imaged and converted into a video signal, and the video signal is converted into binary image data for each pixel, and the mold moves. By determining the coincidence between the reference data and the judgment data, the data obtained by obtaining the locus from the binarized data continuously input while the judgment data is identified,
A method for inspecting a mold product, which comprises determining the quality of the product. 2. A quality inspection device for a molded product in a mold of a mold molding machine, a means for irradiating a point-shaped light having a size into the mold from a fixed position, and the point light source. Means for imaging the pattern appearing in the mold by means of the above, converting it into a video signal, binarizing means for converting the video signal into binary image data for each pixel, and while the mold is moving A means for obtaining the locus from the continuously input binarized data, a means for storing the locus data obtained by the means as a reference data in a normal state, and a metal obtained by the means during the die molding process. Mold molding comprising a judgment means for judging the quality of the molded product by comparing the data of the trajectory of the pattern appearing in the mold with the reference data as judged data and identifying the coincidence. Goods of goods Inspection equipment. 3. A means for irradiating the point-like light is fixed to a movable mold, and the molded product in the fixed mold is inspected by moving with the movement of the mold. The quality inspection device for a mold product according to claim 2. 4. The quality inspection device for a die-molded product according to claim 2, wherein a plurality of means for irradiating the point-like light are installed, and the determination is made according to their respective loci.