JPH02201209A - Injection molding - Google Patents

Abstract

PURPOSE:To set injection molding conditions quickly and properly by a method wherein an image of a surface part of a molded product to which an irradiation light is projected is taken, a ruggedness of the surface of the molded product is detected by processing an image data obtained, and an injection molding control parameter in connected based on the results of the detection. CONSTITUTION:Irradiation light with a specified irradiation pattern is projected on a specified part of a molded product 2 the molded product 2 is taken with photographing means 22 and 24 to make an image data, which is sent to a data processing means 29 and processed to detect a ruggedness of the surface of the molded product 2. Thus, a surface condition of the molded product 2 is converted into a data as image data quickly and properly while the rugged ness of the surface of the molded product 2 is detected quickly without scatter ing. Based on the results of the detection by a data processing means 29, an injection molding control parameter thereof is corrected automatically by a correction means 39. This enables the setting of injection molding conditions quickly and properly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an injection molding method, and more particularly to a method for correcting injection molding conditions depending on the unevenness of the surface of a molded product.

(Prior art) Typical defects in plastic products produced by injection molding include welding and surface distortion, but the above defects are caused by the shape of the mold and product, and
Injection molding conditions such as the oil temperature, injection speed, injection pressure, and holding pressure of the injection cylinder of the injection molding device are also one of the major causes of defects.

Conventionally, when mass producing a certain plastic product by injection molding, multiple molded sample products were molded in advance and the molded sample products were visually inspected, or the molded sample products were measured using a surface roughness meter or dial gauge. By repeating the molding test several times by measuring the defects that occurred on the surface of the plastic product, changing the injection molding conditions based on the data, and molding the molded sample product again, we were able to determine the appropriate injection molding conditions for the plastic product. I was looking for it. Furthermore, even if the injection molding conditions are set in this way, during mass production, the molding condition may change due to variations in the moisture content of the material or the temperature of the hydraulic oil in the injection cylinder, which may cause defects in the plastic product. In such a case, perform the molding test and measure the molded sample again as described above.
Injection molding conditions such as injection pressure were corrected based on experience and intuition.

[Problem to be solved by the invention]

However, with the method described above in which the operator detects defects, measures the defective location, collects data, and determines appropriate injection molding conditions, the injection molding conditions may vary slightly depending on the operator's subjectivity or skill level. There is a problem that subtle defects caused by changes cannot be detected, resulting in a large number of defective products. In addition, when a worker measures a defective location, it takes time to measure, and the measured values vary, making it difficult to determine appropriate injection molding conditions, and when a defect occurs, there is a problem in that the response to the defect is delayed.

An object of the present invention is to provide an injection molding method that can quickly and accurately set appropriate injection molding conditions.

[Means to solve the problem]

The injection molding method according to the present invention projects irradiation light of a predetermined irradiation pattern from a projector onto a predetermined portion of a molded product molded by an injection molding device, and captures an image of the surface portion of the molded product onto which the irradiation light is projected. The image data obtained by the imaging means is processed by the data processing means to detect the uneven state of the surface of the molded product, and based on the detection result, at least one of the injection molding control parameters in the injection molding apparatus is set. The two are automatically corrected by a correction means.

[Effect]

According to the injection molding method according to the present invention, irradiation light of a predetermined irradiation pattern is projected onto a predetermined portion of an injection molded product, and the projected image of the surface portion of the molded product is captured by the imaging means to create image data. The image data is sent to the data processing means, where the image data is processed and the uneven state of the surface of the molded product is detected. Therefore, the surface condition of the molded product is quickly and accurately converted into image data, and the image data is mechanically processed by the data processing means, so the unevenness of the surface of the molded product, i.e. the presence or absence of defects, and the state of the defects. can be detected quickly and without variation.

Further, since at least one of the injection molding control parameters is automatically corrected by the correction means based on the detection result by the data processing means, it is possible to quickly and appropriately set injection molding conditions.

〔Effect of the invention〕

According to the injection molding method of the present invention, as explained in the above [Function] section, it is possible to quickly and accurately detect the presence or absence of a defect in a molded product and the condition of the defect without expending labor or time. The efficiency of inspection work can be improved, and even if a defect occurs in a molded product, the injection molding conditions can be reset quickly and appropriately, reducing the occurrence of defects in molded products and increasing production efficiency. , effects such as being able to improve the quality of molded products can be obtained.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In this example, when a plastic molded product is injection molded using an injection molding device, the most important factor that causes welding or distortion in the molded product among various injection molding conditions is determined depending on the surface condition of the molded product. This is an example in which the present invention is applied to an injection molding method that corrects the injection pressure of a possible injection molding apparatus.

First, to briefly explain the injection molding equipment, the first
As shown in the figure, there is a mold 3 on the left side of the injection molding apparatus 1.
A movable platen 4 for supporting the movable mold 3a of the mold 3 and a fixed platen 5 for supporting the fixed mold 3b of the mold 3 are provided opposite to each other. It can be moved left and right.

On the right side of the injection molding apparatus 1, an injection molding machine main body 8 and an injection cylinder 9 (the illustrated path in FIG. 1) are arranged, and in the middle of the injection molding machine main body 8 there is a hopper 10 filled with plastic material. is provided at the bottom of the hopper 10, a screw cylinder 11 having a spiral plunger therein which functions as a screw conveyor is provided facing in the left-right direction, and an injection part 11a is provided at the left end of the screw cylinder 11, The injection molding machine main body 8 and the injection cylinder 9 are movable in the left-right direction along front and rear guide members 13 by a hydraulic cylinder (not shown).

The spiral plunger inside the screw cylinder 11 is rotationally driven by an electric motor 12, and transfers the plastic material supplied from the hopper 10 inside the screw cylinder 11 toward the injection part 11a.

The injection cylinder 9 is for injecting the plastic material in the screw cylinder 11 into the mold 3 from the injection section 12 at a controlled injection pressure by pushing and driving the spiral plunger to the left by a predetermined stroke. Pressure oil is supplied to the injection cylinder 9, which is a hydraulic cylinder, from a hydraulic pressure supply device 15 via a hydraulic hose 16 and an electromagnetic proportional pressure control valve 14.

A control unit 17 for the molding machine is provided outside the injection molding apparatus l, and this control unit 17 controls the plastic molding process based on commands input from the operation panel and detection signals from various detectors and limit switches. The material supply system, hydraulic supply device 17 and electric motor 12 are controlled.

In front of the mold take-out part 18 of the injection molding apparatus 1, there is an inspection table 19 for taking out the injection molded product 2 from the mold 3.
A take-out robot 20 is disposed to transfer the load to a predetermined position.

To explain the above-mentioned molded product 2, the molded product 2, a simplified example of which is shown in FIG.
The part of the plate part 2a above the lip 2b is the part where welding or distortion is most likely to occur due to shrinkage of the plastic material if the injection pressure of the injection cylinder 9 is not set appropriately during molding.

In addition, since the upper surface of the plate portion 2a corresponds to the parting surface of the mold 3, the periphery thereof has burrs 4 depending on the injection pressure.
1 is likely to occur, and if the injection pressure is too low, a short shot (insufficient injection) will likely cause a short 42 (insufficient build-up) at the peripheral edge of the plate portion 2a (see FIG. 6).

Next, an imaging/data processing apparatus for carrying out the injection molding method unique to the present application will be described with reference to FIGS. 2 to 4.

As shown in FIG. 2, a limit switch 21 for detecting the placement of the molded product 2 is located on the right side of the center of the top surface of the inspection table 19.
A television camera 22 (hereinafter referred to as camera 22) having a solid-state imaging device such as a CCD device is disposed above the center of the plate portion 2a of the molded product 2 placed on the inspection table 19. A floodlight 23 is located near the left of the camera 22.
A television camera 24 (hereinafter referred to as camera 24) similar to the above is disposed above the rear right end of the molded product 2.

A pattern slide 26 on which a concentric pattern 25 is printed is attached to the projector 23 as shown in FIG.
The light is projected obliquely onto a predetermined portion of the upper surface of the plate portion 2a.

When the illumination light of the concentric pattern 25 is projected from the projector 23 equipped with the pattern slide 26, the projected image of the concentric pattern 25 will be distorted depending on the unevenness of the surface due to welds and distortions generated on the surface of the molded product 2. , the projected image is captured by the camera 22, and the image data is processed by the image data processing device 29, thereby forming the molded product 2.
It is possible to detect the uneven state of the surface.

The camera 22 captures a projected image of the surface of the molded product 2 on which the concentric pattern 25 is projected by the projector 23, as shown by the two-dot chain line in FIG. In order to examine the short circuit 40, images of the rear right end and its vicinity are taken, and these images are sent to the image data processing device 29 via image signal processing and storage units 27 and 28, respectively.

As shown in FIG. 4, the image data processing device 29 includes a microcomputer consisting of a CPU 30 (central processing unit), a ROM 31 (read-only memory), and a RAM 32 (random access memory), and an input/output port. 33, D/A converter 34, etc., ROM3
1, an injection pressure control program to be described later is input and stored in advance. Note that the image data processing device 29 is connected to its operation panel 3.
5, command signals etc. can be input.

The limit switch 21 is connected to the image data processing device 29 as shown in the figure, its detection signal is inputted to the microcomputer via the input/output port 33, and the floodlight 23 is connected to the image data processing device 29 via the driver 36. A signal from the microcomputer is output from the input/output port 33 to drive the driver 36 and operate the projector 23.

The cameras 22 and 24 are connected to an image data processing device 29 and image signal processing storage units 27 and 28 as shown in the figure, and are started or stopped by a signal from the image data processing device 29, and images from the cameras 22 and 24 are sent. The image signal processing storage units 27 and 28 are the image data processing device 29
As shown in the figure, they are connected by bidirectional signal lines, and are also connected by a data line for sending image data from the image signal processing and storage units 27 and 28 to the image data processing device 29.

The image signal processing storage units 27 and 28 are connected to a CRT display 38 via a CRT controller 37 as shown in the figure, so that image data can be displayed on the CRT display 38 in response to a command signal from the image data processing device 29. For this purpose, the image signal processing and storage units 27 and 28 include an A/D converter and an image processing processor for processing the image signals from the cameras 22 and 24 into a form that can be processed by the image data processing device 29. A memory capable of storing image data for a screen is provided, and an analog image signal can be output to the CRT controller 37.

On the other hand, the image data input from the image signal processing storage units 27 and 28 to the image data processing device 29 is processed by the injection pressure control program, and the pressure correction control signal obtained as a result is transferred to the input/output port 33 and D/A conversion. The adder/subtractor 39 outputs the analog pressure correction signal ΔP0 through the adder/subtractor 34 as the analog pressure correction signal ΔP0.
is output to.

The adder/subtractor 39 receives the set pressure signal P0 before correction from the control unit 17 of the injection molding apparatus 1.
, and the resulting corrected pressure signal SP is amplified into a drive current DI in the servo amplifier 40 and output to the electromagnetic proportional pressure control valve 14.

The electromagnetic proportional pressure control valve 14 converts the pressure oil supplied from the hydraulic pressure supply device 15 into pressure oil at a pressure corresponding to the drive current DI, and supplies the converted pressure oil to the injection cylinder 9. However, the flow rate control is performed by a flow rate control valve in the hydraulic pressure supply device 15 based on a command from the control unit 17. In this way, by controlling the oil pressure supplied to the injection cylinder 9, the injection pressure of the plastic material injected into the mold 3 can be controlled.

Next, an injection molding method for injection molding the molded article 2 will be described.

The movable mold 3a is attached to the movable platen 4, and the fixed mold 3 is attached to the fixed platen 5.
After attaching the movable mold 3a and the fixed mold 3b, the fixed platen 5 is moved to the right by the clamping cylinder 6, and the movable mold 3a and the fixed mold 3b are combined and clamped. After the mold clamping is completed, the injection molding machine main body 8 moves to the left, the injection part 12 engages with the injection hole of the fixed platen 5, and the injection cylinder 9 is moved to the set injection pressure P set by the control unit 17. The molten plastic material is injected into the mold 3 by hydraulic pressure. After injection molding, molded product 2
After the mold 3 is cooled and solidified, the mold 3 is opened. Based on a command from the control unit 17, the take-out robot 20 takes out the molded product 2 from the mold 3 and transfers it to the inspection table 19.
Transferred to.

When the molded product 2 is placed at a predetermined position on the inspection table 19, the limit switch 21 comes into contact with the lower surface of the plate portion 2a of the molded product 2 and is activated, indicating that the molded product 2 has been placed on the inspection table 18. Detect. This detection signal is transmitted to the image data processing device 29.
is input, and the injection pressure control program is started.

To explain the above injection pressure control, the above set injection pressure P
If the setting is not appropriate, problems such as welding or distortion will occur in the molded product 2.

FIG. 8 shows the relationship between the roundness and the distortion obtained by projecting a concentric circle pattern 25 onto a distorted portion of a molded product and performing image processing. However, the roundness is 1 when there is no distortion, and there is a substantially constant relationship between the distortion and the roundness.

Table 1 shows data showing the relationship between injection pressure, distortion, roundness, paris area, and short circuit, which was separately obtained experimentally using an actual machine.

Table 1 As can be seen from Table 1, as the injection pressure is set lower than the appropriate injection pressure (120 to 122 kg/cd in this experiment), the distortion generated in the molded product 2 increases approximately proportionally. If the injection pressure is set much higher than the appropriate injection pressure, flash will increase, and if the injection pressure is set much lower than the appropriate injection pressure, a short shot will occur in the molded product 2. Therefore, if a defect occurs in molded product 2,
The injection pressure can be corrected based on the following equation.

ΔP-AxK+ -(BxKz -CXK9) In the above formula, A is roundness, B is Paris area, C is short area, K
+・K2・K is a correction coefficient.

The above-mentioned correction coefficients, -, and K, are determined in advance through experiments, and the values are input to the image data processing device 29 from the operation panel 33, or are included in the injection pressure control program as constants.

Next, the injection pressure control routine will be explained based on the flowchart shown in FIG. However, in the figure Si (i=
1.2.3...) indicates each step.

The limit switch 21 is activated and the molded product 2 is placed on the inspection table 19.
Gai! When it is detected that the RA has been placed (Sl), then the RA
M32 memory and image signal processing storage units 27 and 28
Initial settings such as clearing the memory and activating the projector 23 are executed (32), and then the camera 22 is activated, and the camera 22 detects the concentric pattern 25 projected onto the surface of the plate portion 2a of the molded product 2. An image is captured (S3).

FIG. 5 shows an example of an image of the concentric pattern 25 taken by the camera 22, and the concentric pattern 25 is noticeably distorted due to the distortion generated on the surface of the plate 2a.

Next, the image signals for one screen captured by the camera 22 are sequentially sent to the image signal processing storage unit 27, where they are converted into digital image data, and the image data is stored in the internal memory. The storage of the 0 image data to be stored in the memory is completed, and the image data processing device 2
9 confirms the storage (S4), then the image data processing device 29 starts reading the image data (S5),
Next, based on the image data of the concentric circle pattern 25, its roundness A is calculated using a predetermined calculation formula, and the calculation result is RA
It is stored in the memory of M32 (S6).

Next, the camera 24 is activated, and the camera 24 captures an image of the rear right end of the plate portion 2a of the molded product 2 (S7).
. Figure 6 shows burrs 41 and shorts 4 photographed by the camera 24.
This shows the image of No. 2.

Next, the image signals for one screen captured by the camera 24 are sequentially sent to the image signal processing storage unit 28, where they are converted into digital image data, and the image data is stored in the internal memory. Stored. After the image data has been stored in the memory, the image data processing device 2
9 confirms the storage (38), the image data processing device 29 starts reading the image data (S9), and the Paris area B is calculated using the image data, and the calculation result is stored in the memory of the RAM 32. (SlO)0 Next, the short area C due to the short shot is calculated using the same image data as above, and the result is stored in the memory of the RAM 32.

(311).

Next, the calculation result stored in the RAM 32 and the proportionality constant stored in the injection pressure control program or the memory of the RAM 30 in advance are combined with 1.K!・K.

The pressure correction value ΔP of the injection pressure is calculated using the formula ΔP=AXK+
(BXKz CXK2 ) is calculated by (3
12), the calculation result is D/ as the pressure correction signal ΔP0.
It is output to the adder/subtractor 39 via the A converter 34 (S13
), Next, a stop command signal is output to the cameras 22 and 24 to stop their operation, and the operation of the floodlight 23 is also stopped to enter a standby state until the next detection signal from the limit switch 21 is input ( 314).

The pressure correction signal ΔP output by the injection pressure control is added to or subtracted from the set pressure signal P output from the control unit 17 by an adder/subtractor 39, and the correction pressure signal SP resulting from the calculation is sent to the servo amplifier 40. is output,
The injection pressure from the servo amplifier 40 is (P±ΔP) (however, Δ
Drive current D that corrects the oil pressure of the injection cylinder 9 so that when P>0, it is an addition; when ΔP is O, it is a subtraction)
I is output to the electromagnetic proportional pressure control valve 14, which adjusts the oil pressure to appropriately adjust the oil pressure of the injection cylinder 9.

As explained above, according to the injection molding method of this embodiment, the concentric pattern 25 is projected onto the molded product 2, its image is captured by the camera 22, and the image data is used to mold the product by the image data processing device 29. Since a defect occurring in the product 2 is detected, the defect can be detected accurately without expending effort or time.

In addition, the image data processing device 29 calculates a pressure correction value for the injection pressure based on the detection result of the defect, and generates a pressure correction signal ΔP0.
Since the injection pressure is automatically and quickly corrected to an appropriate injection pressure via the oil pressure of the injection cylinder 9, the occurrence of defects in the molded product 2 is reduced, and the quality and productivity of the molded product 2 are improved. I can do it.

In the above embodiment, the TV cameras 21 and 24 were fixedly installed to detect local defects in the molded product 2, but the TV cameras 21 and 24 may be moved while taking images, or the molded product 2 may be It is also possible to detect defects throughout the molded product 2 by moving the molded product 2.

In the above embodiment, defects such as distortion, cracks, and short circuits in the molded product 2 are detected, and the injection pressure, which is an injection control parameter that is dominant in the occurrence of defects, is corrected according to the degree of the defects. In addition to the injection pressure, it is also conceivable to correct the injection speed, the temperature of the molten plastic material, etc.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a plan view of an injection molding apparatus, FIG. 2 is a perspective view showing the imaging state of the camera, FIG. 3 is a plan view of a pattern slide with a concentric pattern, and FIG. Figure 4 is a configuration diagram of the control system, Figure 5 is an explanatory image of a concentric pattern distorted by distortion of the molded product, Figure 6 is an explanatory image of a paris or short at the end of the molded product, and Figure 7 8 is a flowchart of the injection pressure control routine, and FIG. 8 is a diagram showing the relationship between the distortion of the molded product and the roundness of the concentric pattern. 1. Injection molding device, 2. Molded product, 22.24.
- Camera, 23... Floodlight, 25... Concentric circle pattern, 27, 28... Image signal processing storage unit,
29... Image data processing device, 39... Addition/subtraction device, 4
0... Servo amplifier. Patent applicant Mazda Motor Corporation Figure 7 [μm] Gumon fabric

Claims (1)

[Claims] (1) Projecting irradiation light of a predetermined irradiation pattern from a projector onto a predetermined portion of a molded product molded by an injection molding device, and capturing an image of the surface portion of the molded product onto which the irradiation light was projected using an imaging means; The image data obtained by the imaging means is processed by the data processing means to detect the uneven state of the surface of the molded product, and based on the detection result, at least one of the injection molding control parameters in the injection molding apparatus is automatically adjusted by the correction means. An injection molding method characterized by correction.