JPH04163017A - Judging method for defective of nondefective molded article in hot runner type injection molding equipment - Google Patents

Abstract

PURPOSE:To prevent defective articles from mixing with nondefective articles and consequently contrive to improve quality control by a method wherein whether a molded article is defective or nondefective is judged by the value of the sound velocity in resin in a hot runner. CONSTITUTION:Ultrasonic wave having the frequency of 5MHz is emitted at 2000 times/sec from the ultrasonic probe 31 of an ultrasonic flaw detector 30 to a tip part 8. In the ultrasonic flaw detector 30, the ultrasonic probe 31 calculates the value of the sound velocity in resin on the basis of the time (t) between the receipt of a reflected wave 42 and the receipt of a reflected wave 43 (the time (t) represents the transit time of the resin) so as to output it to a comparator 32, which compares the value of the sound velocity with the preset-set value of the sound velocity so as to output the comparison result to a signal generator 33. In the signal generator 33, on the basis of the comparison result, the defective article or nondefective article signal representing whether a molded article is defective or nondefective is outputted to an unloader 32, which takes the molded article out of an opened mold 1 upon the receipt of the defective article or nondefective article signal and carries the molded article either to a defective article yard or to a nondefective article yard.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides a hot runner type injection molding apparatus.
The present invention relates to a method for determining the quality of molded products molded by this apparatus.

(Prior art) Conventionally, during injection molding, the resin in the runner part is kept in a molten state, and after the resin in the cavity is cooled and solidified and taken out, the runner is made into a molten state in the next cycle. A real-runner injection molding apparatus is provided that is configured to inject part of the resin into the cavity.

Such a hot runner type injection molding apparatus attempts to stabilize the resin temperature within the hot runner by appropriately controlling the temperature of a heater disposed in the hot runner.

(Problem to be solved by the invention) However, the resin temperature inside the hot runner often changes due to external factors, and due to variations in resin temperature,
Various molding defects such as filling defects, gate clogging, and flaking occur. Specifically, when the resin temperature of the hot runner decreases, the pressure loss of the molten resin within the hot runner increases, and as a result, the amount of resin injected into the cavity becomes smaller than when molding a good product, causing filling defects. If the resin temperature in the hot runner further decreases, the pressure loss of the molten resin will further increase, causing gate clogging. Also,
When the resin temperature inside the hot runner increases, the pressure loss of the molten resin inside the hot runner decreases, and as a result, the amount of resin injected into the cavity becomes larger than when molding a good product, resulting in overfilling and formation of cracks. .

Although the various molding defects described above occur due to temperature changes in the resin within the hot runner, inspectors determine whether the molded product is good or not.
There was a problem in which accidents occurred where defective products were mixed with non-defective products due to the inspector's carelessness. It was also an impediment to automation.

(Means for Solving the Problems) A method for determining the quality of a molded product in a hot runner injection molding apparatus of the present invention is a method for determining the quality of a molded product in a hot runner injection molding apparatus. While transmitting an ultrasonic wave toward the runner, the reflected wave of the ultrasonic wave reflected by the hot runner is received, and after calculating a sound speed value based on the received reflected wave, this sound speed value is set in advance. It is determined whether the sound velocity value is within an allowable range or not, and based on this result, the quality of the molded product is determined.

(Function) During injection molding, the ultrasonic flaw detector calculates the sound velocity value of the resin based on the reflected waves received by the ultrasonic probe and outputs it to the comparator. The comparator compares this sound speed value with a set sound speed value, determines whether the sound speed value is within an allowable range of the preset set sound speed value, and outputs the result to the signal generator. Based on this result, the signal generator determines whether the molded product is defective or non-defective.

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

FIG. 1 shows a part of a general hot runner mold for carrying out the method for determining the quality of molded products in a hot runner injection molding apparatus according to the present invention.

In the figure, ■ is a mold, and mold l is a fixed mold 2 and a movable mold 3.
It is made up of. 5 is a sprue that communicates with the tip of an injection nozzle (not shown) during injection molding.

A hot runner 6 is connected to the sprue 5, and the hot runner 6 is composed of a manifold part 7 and a chi-knob part 8. A manifold heater 10 is disposed in the manifold main body 9 in which the manifold section 7 is formed in proximity to the manifold/L/F section 7, and
A heater (spear) 11 attached to the manifold main body 9 is inserted into the tip portion 8, and the temperature of the resin staying in the hot runner 6 is adjusted by these manifold heaters 10 and 11.

The tip of the tip portion 8 of the hot runner 6 is communicated via a gate with a cavity 12 formed facing the dividing plane between the fixed mold 2 and the movable mold 3.

In addition, the reference numeral 13 in the figure is a runner bush provided on the circumferential surface of the tip portion 8, 15 is a spear head provided at the tip of the heater 11, 16 is a fixed side mounting plate, I7 is a locate ring, and 18 is a A spacer block 20 is a plug presser for holding down the runner plug 21.

An ultrasonic probe 31 connected to an ultrasonic flaw detector 30 shown in FIG. 2 is provided on the outer peripheral surface of the runner bush 13.

The ultrasonic probe 31 uses the ultrasonic flaw detector 30 to transmit ultrasonic waves of 5 MHz toward the tip portion 8 of the real runner 6, for example, 2000 times per second (the number of times of transmission can be changed arbitrarily). This emitted ultrasonic wave is transmitted to the tip section 8.
After passing through the inner resin and being reflected by the outer peripheral surface of the heater If, the waves pass through the resin again as reflected waves (echo waves), are received by the ultrasonic probe 31, and are input to the ultrasonic flaw detector 30.

The ultrasonic flaw detector 30 calculates the sound velocity value based on the reflected waves. That is, the sound velocity value of the resin filled in the chip portion 8 is calculated.

Here, the sound velocity value calculated by the ultrasonic flaw detector 30 changes depending on the change in the resin temperature of the molten resin. This is because as the resin temperature increases, the density of the molten resin decreases, which causes the sound velocity value to become smaller (slower), and conversely, as the resin temperature decreases, the density of the molten resin increases, which causes the sound velocity value to increase (faster). It's for a reason.

As shown in FIG. 2, the ultrasonic flaw detector 30 is connected to a comparator 32 into which the sound velocity value calculated by the ultrasonic flaw detector 30 is input. The comparator 32 compares the calculated sound speed value with a preset sound speed value. This set sound velocity value is determined by measuring the sound velocity value of the resin in the hot runner 6 in advance when a non-defective molded product is obtained during injection molding, and setting the allowable range of the sound velocity value that allows a non-defective product to be obtained based on this measurement. .

Further, the comparator 32 is connected to a signal generator 33 to which the comparison result of the comparator 32 is input. Based on this comparison result, the signal generator 33 outputs a pass/fail signal to the take-out machine 35, indicating whether the molded product is defective or non-defective. The take-out machine 35 is a conventionally known device that takes out the molded product from the opened mold 1, and upon receiving a pass/fail signal from the signal generator 33, transports the taken-out molded product to a defective product storage area or a non-defective product storage area.

In this way, a real runner injection molding apparatus is constructed.

Next, a method for determining the quality of a molded product using the hot runner injection molding apparatus configured as described above will be described.

First, molten resin injected from an injection nozzle of an injection molding machine (not shown) is filled into the cavity 12, and
The sprue 5 and hot runner 6 that serve as the route for this are also filled. Along with this, the ultrasonic flaw detector 30 transmits 5 MHz ultrasonic waves from the ultrasonic probe 31 toward the tip portion 8 2000 times per second.

FIG. 3 shows reflected waves of ultrasound received by the ultrasound probe 31 after transmitting ultrasound from the ultrasound probe 31 as described above.

In FIG. 3, reference numeral 41 indicates a transmitted wave, and reference numeral 42 indicates an inner circumferential surface 13a of the runner bushing 13 (the fourth
The reflected wave 43 is reflected by the outer circumferential surface 11a of the heater 11 after passing through the resin in the chip part 8 (see FIG. 4).
The reflected wave 45 is reflected by the ultrasonic probe 31 and returns to the inner peripheral surface 13 of the runner bushing 13.
This is a secondary reflected wave of the reflected wave 42 reflected by a.

In addition, in the ultrasonic probe 31, after the secondary reflected wave 45, the reflected wave 43 is reflected by the ultrasonic probe 31, and the secondary reflected wave 43 is reflected again by the outer peripheral surface 11a of the heater 11. While the reflected waves are received, tertiary and fourth-order reflected waves obtained by reflecting these secondary reflected waves again are also received, but these will not be specifically mentioned here.

Then, the ultrasonic flaw detector 30 detects the resin based on the time t (this time t is the resin passage time) from when the reflected wave 42 is received by the ultrasonic probe 31 to when the reflected wave 43 is received. The sound velocity value of is calculated and output to the comparator 32. The comparator 32 compares this sound speed value with a preset sound speed value and outputs the comparison result to the signal generator 33. Based on this comparison result, the signal generator 33 outputs a pass/fail signal to the take-out machine 35, indicating whether the molded product is defective or non-defective. Then, the take-out machine 35 receives the pass/fail signal and takes out the molded product from the opened mold 1 and transports it to a defective product storage area or a non-defective product storage area. Specifically, if the sound velocity value calculated by the ultrasonic flaw detector 30 is within the allowable range of the set sound velocity value, a good product signal is output from the signal generator 33 to the take-out machine 35, and the mold is opened by the take-out machine 35. The molded product is removed from mold 1 and transported to the good product storage area. Further, if the calculated sound velocity value is not within the allowable range of the set sound velocity value, a defective product signal is output from the signal generator 33 to the take-out machine 35 and the take-out machine 3
The molded product is taken out from the mold 1 opened in step 5 and transported to the defective product storage area.

FIG. 5 shows another embodiment.

In this example, the ultrasonic probe 31 is installed in the cavity 12 of the fixed type 2.
The hot runner 6 is provided in the vicinity of the hot runner 6 and is configured to transmit ultrasonic waves from the ultrasonic probe 31 toward the tip of the tip portion 8 of the hot runner 6 .

Note that the other configurations are similar to those of the previous embodiment, and the same members are given the same reference numerals. Furthermore, the method for determining the quality of the molded product is the same as in the previous embodiment, and its explanation will be omitted.

Note that it is not always necessary to take out the molded products using the take-out machine 35 and to sort them into good and defective products as described in this example. For example, if the take-out machine 35 is not installed, the worker is informed whether the molded product is defective or non-defective by lighting a lamp or sounding a buzzer based on the pass/fail determination method of the present invention. This worker may also sort defective products and non-defective products.

(Effects of the Invention) As described above, according to the method of the present invention, the sound velocity value of the resin in the hot runner is calculated, and it is possible to determine whether the molded product is a defective product or a non-defective product based on this sound velocity value. During molding, it is possible to determine which products are defective due to filling defects, gate clogging, or flaking, and it is possible to prevent defective products from being mixed with non-defective products, thereby improving quality control. can. Furthermore, automation can be achieved by controlling the operation of another device such as a take-out machine based on this determination result.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing a part of a hot runner type mold, Figure 2 is a block diagram showing the configuration of a hot runner type injection molding device, and Figure 3 is a reflection received by an ultrasonic probe. Figure 4 is a partially enlarged view of the area around the ultrasound probe, Figure 5 shows the waves.
The figure is a sectional view showing a part of another real runner type mold. ■...Mold 6...Hot runner 30...Ultrasonic flaw detector 31...Ultrasonic probe 32...Comparator 33...Signal generator Patent applicant Sekisui Chemical Co., Ltd. Representative Hiro 1) Kaoru・1′111゛・” Figure 5

Claims (1)

[Claims] 1) In a hot runner type injection molding device, an ultrasonic probe installed in the mold emits ultrasonic waves toward the hot runner and receives reflected waves of the ultrasonic waves reflected by the hot runner. After calculating the sound speed value based on the received reflected waves, it is determined whether this sound speed value is within the allowable range of the preset sound speed value, and based on this result, the quality of the molded product is determined. 1. A method for determining the quality of a molded product in a hot runner injection molding apparatus.