JPH0587371B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a color change control method and device for an injection molding machine, and in particular to a color change control method and apparatus that uses transmitted light and reflected light of a molten resin as a reference for the color change start color. This invention relates to a new improvement for determining the completion of color change by determining the change in color difference during color change when .

[Prior Art] There are various color change control methods for this type of injection molding machine that have been used in the past, but the following two methods are generally used.

(1) When changing the color of the molten resin in the cylinder and nozzle of an injection molding machine from resin A, which has a different color, to resin B, the temperature of the cylinder and nozzle must reach the specified temperature required for molding resin B. After confirming that the color of resin B has changed, the molder manually measures an appropriate amount and performs an air purge, and then repeats the measurement and air purge an arbitrary number of times to confirm that the predetermined color of resin B has changed. You can perform the checking process by trial and error, or you can use the automatic purge circuit to input empirical values for metering stroke, back pressure, purge speed, and number of purges in advance and automatically change the color. There were two methods: to confirm that the color of resin B had changed to the predetermined color.

(2) In addition, when changing the color by injection into a mold, or when controlling the color variation of a molded product during normal molding, after taking out the molded product, judgment by human eyes or Quantitative judgments were made using hue and color difference discriminators.

[Problems to be Solved by the Invention] Since this conventional color change control method for an injection molding machine was configured as described above, the following problems existed.

That is, in the case of the conventional method (1), the molding worker manually operated the molding, which required manpower, and it was difficult to improve the work efficiency and reduce the cost. Furthermore, since color discrimination is performed based on the molder's experience and intuition, it is qualitative and has large errors, causing problems in product quality.

Furthermore, in the latter case of conventional method (1), automation is possible, but depending on the setting conditions such as the number of times of purging, there is a possibility that the operation may be stopped even if the color change is not necessarily completed.

In addition, in conventional method (2), since color difference discrimination is performed after the molded product is taken out, there is a large time lag and it is not useful for controlling feedback to the next shot molding conditions. However, there was a problem in that it was only possible to do so, and it was not true online measurement and control.

The present invention has been made to solve the above-mentioned problems, and in particular, uses transmitted light and reflected light of molten resin to measure the color difference change during color change when the color at the start of color change is used as a reference. It is an object of the present invention to provide a color change control method and device for an injection molding machine that determines whether color change is complete or not.

[Means for Solving the Problems] A color change control method for an injection molding machine according to the present invention changes the color of molten resin in a cylinder of an injection molding machine to the color of another new resin introduced into the cylinder. In the color change control method for an injection molding machine, a first step of irradiating light to a molten resin in a nozzle or mold communicating with the cylinder, and a step of irradiating light transmitted from the molten resin or surface reflected light. The light is taken into the color identification sensor via the light receiving optical fiber at a certain time during pressure holding and cooling, and is quantified into color quantitative values R, G, and B values for each shot by a computing unit before the next injection, and the color is changed. After the start of sampling, the second shot is converted into a color difference ΔE from the quantitative color value of the first shot.
process, the color difference ΔE(i) of the i-th shot, and the (i-th)
1) The third step of comparing the difference from the shot color difference value ΔE(i-1), that is, the rate of change of the color difference value: [ΔE(i)-ΔE(i-1)] with the set values A and B. After the rate of change of the color difference value becomes equal to or greater than the set value A, and after the color change operation continues, when the comparison condition becomes equal to or less than the set value B, a completion signal is issued indicating that the color change is completed, and the comparison condition is This method continues the color changing operation when the condition is not satisfied.

Further, the color change control device for an injection molding machine according to the present invention changes the color of the molten resin in the cylinder of the injection molding machine.
In a color change control device for an injection molding machine that changes the color of a different new resin to be introduced into the cylinder, a projecting light that irradiates light onto a nozzle communicating with the previous cylinder or the molten resin in the mold. fiber and
A light-receiving optical fiber for receiving transmitted light or reflected light from the molten resin, a color discrimination sensor for color discrimination of the light, a computing unit connected to the color discrimination sensor, and a computing device for the first half. and a setting device connected to the device for setting set values A and B, and the first calculation device obtains the color quantitative values R, G, and B values, and calculates the color difference from the color quantitative values R, G, and B values. Get ΔE(i), and calculate the color difference ΔE of the shot before each shot.
The configuration is such that the rate of change [ΔE(i)−ΔE(i−1)] with respect to (i−1) is calculated.

More specifically, it includes a comparator connected to the arithmetic unit, which compares the rate of change of the color difference ΔE with set values A and B, and generates a color change completion signal when the comparison conditions are met. This is the method I used.

More specifically, the light-emitting optical fiber and the light-receiving optical fiber are provided in the high-hardness glass of the transparent window of the cylinder.

More specifically, the light emitting optical fiber and the light receiving optical fiber are fixed by a fiber fixing jig.

[Function] In the color change control method and device for an injection molding machine according to the present invention, transmitted light or surface reflected light from the molten resin is sent to the color discrimination sensor at a certain time during pressure holding and cooling through the light receiving optical fiber. Capture and quantify each shot into color quantitative values R, G, and B values by a calculator just before the next injection, and after the start of color change,
Convert the color difference ΔE from the quantitative color value of the first shot at the start of sampling to the color difference value ΔE(i) of the i-th shot.
and the color difference value ΔE(i-1) of the (i-1)th shot
, that is, the rate of change in color difference value [ΔE(i)−ΔE(i
-1)] with set values A and B, and as a result,
After the rate of change of the color difference value becomes equal to or greater than the set value A, and furthermore, after the color change operation continues, when the comparison condition becomes equal to or less than the set value B, a completion signal is generated indicating that the color change is completed.

Further, when the comparison condition is not satisfied, by continuing the color change operation, it is possible to confirm the color change so that the comparison condition is satisfied.

[Embodiments] Hereinafter, preferred embodiments of the color change control method and apparatus for an injection molding machine according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block configuration diagram with a sectional view showing a color change control method and apparatus for an injection molding machine according to the present invention. A heater 2 is provided around the outer periphery.

A screw 3 is rotatably provided in the guide path 1 in the cylinder 1, and this screw 3 has the following features:
It is configured to be rotatable and axially movable by means of a drive source 5 connected via a coupling ring 4. A nozzle 6 having a discharge hole 6a is attached to the tip 1b of the cylinder 1,
Two mounting holes 30 are formed on the circumferential surface of the nozzle 6, facing each other and communicating with the discharge hole 6a.
Transparent windows 9 made of high-hardness glass 7 and high-hardness steel 8 with excellent pressure resistance, heat resistance, and translucency, and sealing members are inserted into the mounting holes 30, respectively, and fixed to the nozzle 6 with fiber fixing jigs 10. It is screwed together so that it can be installed.

The light emitting optical fibers 12 and 12' connected to the light source 13 provided outside the nozzle 6 and the light receiving optical fiber 20 connected to the color identification sensor 14 are connected to the high hardness glass 7 of the transparent window 9. a set bolt 11 attached to the fiber fixing jig 10 and provided in close contact with the end of the fiber fixing jig 10;
By tightening the optical fibers 12,1
2' and 20 are fixed. Further, sampling is started by a sampling signal 21 that is generated when pressure holding is completed, and this sampling signal 21 is input to the color identification sensor 14,
The output value from this color identification sensor 14 is converted into a digital value 17a by an A/D converter 17 via an amplifier 15 and an interface 16, and is then converted into a digital value 17a by a computer 18 for each shot just before the next injection. The digital value 17a is quantified into color quantitative values R, G, B values, and the color difference ΔE from the color quantitative value of the first shot at the start of sampling is calculated. value and/or
Display ΔE.

On the other hand, the rate of change for each shot of the color difference ΔE set in the setter 22 is compared to the set values A and B sequentially by the comparator 2.
4, and when the rate of change becomes greater than A and then less than B, a color change completion signal is issued, and if not, the color change operation is continued.

Further, the color change start signal 25 is transmitted to the controller 26
and the signal 2 from this controller 26
6a is input to the drive source 5 via an amplifier 27.

Here, the light-emitting optical fibers 12, 12' and the light-receiving optical fiber 20 are preferably of a flexible type, but may be of a straight type. Furthermore, optical fiber 1 for light projection
Although the light-receiving optical fibers 2' and the light-receiving optical fibers 20 are illustrated as being separated, it goes without saying that the same effect can be obtained even if a large number of ultra-thin diameter optical fibers are arranged in a scattered manner. Furthermore, the sampling signal has the same effect even when the pressure holding is completed and when there is little resin flow.

Next, the color change control method according to the present invention will be described in more detail according to the flowchart of FIG.

Start molding or purge (1st step: 30)
After that, when the sampling start signal 21 is turned ON (third step: 32) with the color change start signal 25 (second step: 31) and the resin to be changed is put in and molding or purging is continued, From the light source 13 ON (fourth step: 33), the light emitting optical fibers 12, 12' and the nozzle 6 are transmitted through the transparent window 9.
The wavelength of the light received from the resin 1A is transmitted through the transparent window 9 and the light-receiving optical fiber 20 to the color discrimination element 14, amplifier 15, interface 16, and A/D converter 17. The color difference values are separated into R, G, and B values (fifth step: 34), and the R, G, and B values are converted into X, Y, and Z values by the arithmetic unit 18 (sixth step: 35). Furthermore, the X, Y, and Z values are converted into L, a, and b values (seventh step: 36).

The conversion formula is ^the general formula ^{: 2} b = 7.0 (Y - 0.847Z) / Y ^1/2 ...... is used.

The sampling start shot is set as the first shot, and the L, a, and b values of each subsequent shot are calculated by the calculator 18 before the next shot is ejected, and L(i), a(i), and b are calculated.
Store it in memory as (i) (8th step: 37).

Next, the computer 18 calculates the i-th shot L(i), a
Calculate the difference between (i), b(i) and the first shot L(1), a(1), b(1) as ΔL(i), Δa(i), Δb(i). Memorize it (9th step: 38).

ΔL(i)≡L(i)−L(1) Δa(i)≡a(i)−a(1) Δb(i)≡b(i)−b(1) …… Next, the calculation unit 18 Then, the color difference ΔE(i) between the i-th shot and the first shot is calculated (10th step: 39). The conversion formula is generally as follows: ΔE(i) = [(ΔL(i)) ² + (Δa(i)) ² + (Δb(i)) ²
] ^1/2
Use...

Here, the formula is "New Edition Color Science Handbook"
For P.92, formula, the well-known formula described in "JIS" P.1401 was used.

After displaying the color difference ΔE(i) of the i-th shot on the y-axis and the number of shots on the x-axis for each shot as shown in FIG. 3 (11th step: 40), the i-1st shot is The difference between the i-th shot and the i-th shot, that is, the rate of change in color difference, is compared with the set value A, and when the rate of change exceeds the set value A, the flag F is set to 1 (12th step: 41) and the color change is continued. And the j-1st
The difference between the color difference value of the shot (i<j-1) and the j-th shot, that is, the rate of change in color difference, is compared with a set value B, and when the rate of change becomes equal to or less than B,
(0≦B<A) A color change completion signal is issued, and if the rate of change does not become less than B, the color change operation is continued.

Here, (i, ΔE(i)) is displayed as a shot graph every time, but it is also possible to display them all at once after the color change completion signal is turned on.

In addition, in this example, the rate of change of color difference ΔE [ΔE(i)−
[Delta]E(i-1)] was compared with the set values A and B, but it may also be compared with the set values using a differentiator.

Further, although the present invention has been described as an example in which color difference discrimination is performed by detecting color in a nozzle part, the same effect can be obtained even if it is applied to an in-mold sprue part, a runner part, and a cavity part of a mold (not shown). Needless to say.

[Effects of the Invention] Since the color change control method and device for an injection molding machine according to the present invention are configured as described above, the following effects can be obtained.

That is, the wavelength of the color of the molten resin is captured from the transmitted light that has passed through the molten resin or the reflected light that has been reflected through the molten resin via a light-receiving optical fiber, and is quantified into R, G, and B values by a calculator. Then, it is converted into a color difference ΔE(i) from the color quantitative value of the first shot at the start of sampling, and the change rate of color difference (ΔE(i)−ΔE(i
-1)) After a large change, a color change completion signal is automatically issued when it becomes extremely close to zero, that is, when there is no change in color, so errors can be reduced and labor savings can be achieved.

[Brief explanation of the drawing]

FIG. 1 to FIG. 3 are for showing a color change control method and device for an injection molding machine according to the present invention.
FIG. 1 is a block diagram with a sectional view showing the overall configuration including the control system of the injection molding machine, FIG. 2 is a flow chart showing the control method, and FIG. 3 is a characteristic diagram showing the relationship between the number of shots and color difference. 1 is a cylinder, 1A is a molten resin, 6 is a nozzle,
7 is high hardness glass, 9 is a transparent window, 10 is a fiber fixing jig, 12, 12' is an optical fiber for light projection,
14 is a color identification sensor, 18 is an arithmetic unit, 20 is an optical fiber for light reception, 22 is a setting device, 23 is a color change completion signal, and 24 is a comparator.

Claims (1)

[Scope of Claims] 1. A color change control method for an injection molding machine in which the color of the molten resin 1A in the cylinder 1 of the injection molding machine is changed to the color of another new resin introduced into the cylinder 1. , a first step of irradiating light onto the nozzle 6 communicating with the cylinder 1 or the molten resin 1A in the mold, and transmitting the transmitted light or surface reflected light from the molten resin 1A through a light-receiving optical fiber 20. , holding pressure/
At a certain time during cooling, the color is captured in the color identification sensor 14, and the arithmetic unit 18 quantifies each shot into quantitative color values R, G, and B before the next injection, and after the start of color change, the first shot starts sampling. A second step of converting the color difference to the quantitative color value ΔE; and the difference between the i-th shot color difference value ΔE(i) and the (i-1)th shot color difference value ΔE(i-1), that is, the color difference. Rate of change of value: [ΔE(i)-ΔE(i-1)] and set values A and B
After the rate of change of the color difference value becomes equal to or greater than the set value A, and after the color change operation continues, when the comparison condition becomes equal to or less than the set value B, the color change is determined to be completed. A color change control method for an injection molding machine, characterized in that when a completion signal is issued and the comparison condition is not satisfied, the color change operation is continued. 2. A color change control device for an injection molding machine configured to change the color of the molten resin in the cylinder 1 of the injection molding machine to the color of another new resin introduced into the cylinder 1, which communicates with the cylinder 1. Light projecting optical fibers 12, 12' that irradiate light onto the molten resin 1A in the nozzle 6 or the mold; and a light receiving optical fiber 20 that takes in transmitted light or reflected light from the molten resin 1A. A color identification sensor 14 for identifying the color of the light, an arithmetic unit 18 connected to the color identification sensor 14, and a setting device 22 connected to the arithmetic unit 18 for setting set values A and B.
The arithmetic unit 18 calculates the color quantitative value R,
In addition to obtaining the G and B values, the color quantitative values R, G, B
The color difference ΔE(i) is obtained from the value, and the rate of change [ΔE(i)−ΔE(i
-1)] A color change control device for an injection molding machine, characterized in that it is configured to calculate. 3. A comparator 24 connected to the arithmetic unit 18, which compares the rate of change of the color difference ΔE with set values A and B, and generates a color change completion signal 23 when the comparison conditions are satisfied. 3. The color change control device for an injection molding machine according to claim 2. 4. The injection molding according to claim 2 or 3, wherein the light emitting optical fibers 12, 12' and the light receiving optical fibers 20 are provided on a high hardness glass 7 of a transparent window 9 of the cylinder 1. Machine color change control device. 5. The color change control device for an injection molding machine according to claim 4, wherein the light emitting optical fibers 12, 12' and the light receiving optical fiber 20 are fixed by a fiber fixing jig 10.