JPS61182920A - Quality judging device of molded article in injection molding machine - Google Patents

Abstract

PURPOSE:To judge quality correctly and precisely, by a method wherein a moving period of time of a protrusion between moving positions each is measured by detecting moving positions of the protrusion between two points, which is compared with a preset reference period of time corresponding to the quality of a molded article. CONSTITUTION:A quality deciding device 1 is provided with a detecting rod 50 fitted unitarily to a protruding plate 31. The rod 50 possesses a detecting dog 51 on an end part. Approach switches 52, 53 are connected respectively with a time instrument 54. The instrument 54 is provided with a built-in timer which is started when the original approach switch 52 is turned ON and suspened when the next approach switch 53 is turned ON. With this construction, a moving period of time of the detecting dog 51 between both the switches 52, 53 is measured and made into a detected period of time To. A presetting device 56 presets reference period of times corresponding to quality of a molded article 3 into the upper limit period of time Tu and the lower limit period of time TL. The Tu and TL can be preset arbitrarily variably according to a kind of the molded article. The detected period of time To and reference periods of times (Tu, TL) and supplied respectively to a comparator 55, and as for the comparator 55, judging signals deciding that the title molded article is excellent when TL<=To<=Tu is given and that the article is defective when To>TL or Tu<To is given are put out.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a quality determination device for molded products in an injection molding machine that can easily determine whether a molded product is a good product or not.

(Prior Art) In injection molding using thermoplastic resin, various quality determination devices have been proposed for determining defective molded products that occur during molding.

Typical examples include those that monitor the resin pressure in an injection cylinder or mold cavity, or those that monitor the oil pressure of a hydraulic circuit that drives an injection plunger.

The principle of these determination devices is to monitor the pressure change and determine whether the product is good or defective, considering that molding defects occur when the pressure at a predetermined location is out of the appropriate range. Normally, pressure is detected by placing a pressure sensor directly in front of the area where pressure is to be detected.

(Problem to be Solved by the Invention) However, all of the conventional quality determination devices including this device monitor the resin pressure or oil pressure during the injection filling process, so pressure must be monitored in a very short period of time. For this reason, accurate monitoring is difficult and requires particularly advanced molding knowledge.

In addition, only the pressure during the injection filling process can be monitored, and it is not possible to comprehensively and accurately monitor the effects of other factors that affect quality, such as resin temperature, mold temperature, and injection speed. Can not.

Furthermore, a pressure sensor with high sensitivity and high strength is required, and the structure for mounting the sensor becomes complicated, and its operation becomes difficult, resulting in a significant increase in cost and poor appearance of the molded product. However, the reality is that it is difficult to put it into practical use and for general use.

Therefore, the present invention eliminates the above-mentioned problems and provides a quality determination device for molded products in an injection molding machine that can perform accurate and appropriate determinations and can be easily implemented at low cost. It is something to do.

(Means for Solving the Problems) As shown in FIG.
This relates to a molded product quality determination device 1 applied to
A detection means 6.7 for detecting the movement position between points P1.22, a time measurement means 8 for measuring the movement time (detection time To) of the protrusion 5 between the respective movement positions P1.22,
Reference time setting means 9 for setting the travel time (reference time: upper limit time Tu, lower limit time TL) corresponding to the quality of the molded product 3
, the detection time To and the reference time (Tu, TL)
The present invention is provided with a comparison processing means 10 for comparing the results and outputting the comparison results.

(effect) Next, the operation of the present invention will be explained.

First, the mold release process is as follows. The mold 4 into which the material has been injected is opened by moving the movable mold 12 as shown in FIG. The ejecting means 2 is then actuated by the hydraulic circuit 13. As a result, the protruding portion 5 gradually protrudes, and the molded product 3 is released from the mold.

By the way, the magnitude of the injection filling pressure greatly affects the quality of the molded product, and if the pressure is too low, molding defects such as insufficient filling (short shot) where the mold cavity is not completely filled with the molding material will occur, and on the other hand, It is known that when the pressure is too high, overfilling of the molding material causes over-punk phenomenon and molding defects such as fringing.

On the other hand, the magnitude of the injection filling pressure also has a correlation with the mold release resistance. That is, as shown in FIG. 3 (injection filling pressure vs. ejection force characteristic diagram), when the filling pressure increases, the adhesion force of the molded product 3 into the cavity increases approximately in proportion, and the mold release resistance also increases. As a result, the moving time for the predetermined period when the protruding portion 5 is protruded also increases. Note that the filling pressure also changes the quality of the molded product 3, such as its weight and dimensions. Therefore, the quality of the molded product 3 can be determined by detecting the moving (detection) time To of the protruding portion 5 in the protruding means 2 when the protruding portion 5 is protruded.

Therefore, the moving time To between the moving positions P1 and 22 of the protruding portion 5 is measured by the time measuring means 8, and the reference time (Tu and TL) from the reference time setting means 9 is compared by the comparison processing means 10, and TL≦ If To≦Tu, the product is determined to be good, and if TL>To or Tu<To, it is determined to be defective, and a determination signal corresponding to the good product is output.

(Example) Below, preferred examples according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a longitudinal sectional view of an injection molding machine including a quality determination device according to the present invention.

First, in order to clarify the present invention, the overall configuration of an injection molding machine will be described. The injection molding machine M is an example of a set of in-line screws, and this molding machine M includes an injection cylinder 20 and a screw 21 inserted into the injection cylinder 20 so as to be rotatable and movable back and forth.

The injection cylinder 20 has a nozzle 22 at its tip, and a fixed mold j4 fixed to a fixed platen 23 receives coal into this nozzle 22. The movable mold 12 is disposed opposite to the fixed mold 14, and the movable mold 12 is connected to the fixed mold 1 by an integral movable plate 24.
4 on a tie bar (not shown). Fixed type 14
The movable mold 12 constitutes a mold 4, which is a known injection mold having a cavity 15, a gate 16, a runner 17, and a sprue 18.

On the other hand, the movable mold 12 is provided with a protruding pin 30 facing each cavity, and this pin 30 is attached to a protruding plate 31 integrated at the rear end.
It moves forward and backward. The protrusion Fj, 31 and the protrusion pin 30 constitute the protrusion 5.

The projecting plate 31 is further integrally connected to a projecting piston 33 inserted into a projecting cylinder 32 integral with the movable platen 24.

In addition, hydraulic pressure #41 is connected to the front oil chamber 34 and rear oil chamber 35 of the protruding cylinder 32 via a switching valve 40, thereby selectively supplying pressure oil to the front oil chamber 34 or the rear oil chamber 35. A hydraulic circuit 13 that can be constructed.

Therefore, in the mold release process, by supplying pressure oil to the rear oil chamber 35, the ejection piston 33 moves forward in the ejection direction,
The protruding handle 31 and the ejecting pin 30 also move in the protruding direction. As a result, when the mold is opened, the molded product 3 is released from the mold by the ejecting action of the ejecting pin 30 as shown in FIG.

The cycle process for such injection molding (JMM) is as follows.

First, after the mold release process is completed, the movable mold 1 is moved by the operation of the mold clamping ram 25.
2 and the fixed mold 14 are closed. Next, the process moves to an injection filling process. In the same process, the screw 21 is
moves forward and fills the cavity 12 with the material W accumulated in front of it. Thereafter, the material W is accumulated in front of it by the rotation of the screw 21, and the mold is opened as shown in FIG. 1 after a required cooling time.

At this time, the molded product 3 is attached to the movable mold 12 side and taken out from the cavity of the fixed mold 14. Therefore, after the mold opening is completed or during the mold opening, the ejecting means 2 may be operated to perform the above-mentioned mold release process, and the -cycle process is thus completed.

Next, the molded product quality determination device 1 will be specifically explained. The device 1 first includes a detection rod 50 that is integrally attached to the protrusion plate 31.

Therefore, the rod 50 is displaced following the displacement of the protruding plate 31, and has a detection dog 51 at its end. on the other hand,
Proximity switches 52 and 53 are disposed facing two different positions on the movement trajectory of the detection dog 51. The proximity switches 52, 53 are turned on when the detection dog 51 is located at the position of each switch 52, 53.

Thereby, two moving positions of the protrusion plate 31 can be detected. Note that it is desirable that the proximity switch 52, which is first detected when the mold is opened, detects the initial position of the protrusion plate 31 as much as possible.

For this reason, it is usually preferable to provide it at the forward movement start position of the protruding plate 31, and in this case, it can also be used as a position detector for the backward limit of the protruding plate 31. In addition, at this time, the measurement of the moving time is started by the signal of the command to start moving the protrusion (switching valve 13).
(switching signal, etc.).

Further, the proximity switches 52 and 53 are each connected to a time measuring device 54. The measuring device 54 has a built-in timer, and this timer starts when the first proximity switch 52 is turned on and stops when the next proximity switch 53 is turned on. As a result, the moving time of the detection dog 51 between both switches 52 and 53 is measured, and is set as the detection time To. This detection time To is converted into a voltage value and applied to the comparator 55, for example.

On the other hand, a reference time setting device 56 is provided, and this setting device 56 sets a reference time corresponding to the quality of the molded product 3. The reference time is set by converting it into a corresponding voltage value, and is set as an upper limit time Tu and a lower limit time TL. Note that the times Tu and T can be arbitrarily set variably depending on the type of molded product, such as size, shape, material, etc.

The detection time To and the reference time (Tu, TL) are respectively supplied to the comparator 55, and in the comparison P555, as described above, the condition of TL≦ToS Tu is satisfied and a good product (for example, a high level signal) is determined. Since Tu′<To, a determination signal indicating that the product is defective (for example, a low level signal) is output. This determination signal may be amplified by an amplifier 57 and directly supplied to the i-report means, and the tuning fork may be used as an activation signal to activate an alarm by prior means, or it may be supplied to a sorting device to distinguish between defective and non-defective products. may be used as a control signal for automatic selection.

FIG. 2 is a flowchart illustrating the functions of the quality determination device 1 according to the above embodiment.

Although the embodiments have been described above, the present invention is not limited to these embodiments. For example, the proximity switches 52 and 53 can use any detection means capable of detecting position, such as a detector such as an encoder, an optical detector, or the like. Also ratio/editing 55
may be any electrical circuit, or may use a microcomputer. Furthermore, the detection means and the measurement means are not limited to the examples shown above, and any means capable of detecting the moving time of the protrusion may be used. Furthermore, the ejection cylinder 32 serving as the driving source for the ejection means 2 may be of a hydraulic type or a pneumatic type. Note that when a hydraulic cylinder is used, the detected blueness can be further increased if the hydraulic power source is equipped with an accumulator function. Any other changes in the shape, structure, arrangement, quantity, etc. of details that do not depart from the gist of the present invention are permitted within the scope of the present invention.

(Effects of the Invention) As described above, the apparatus for determining the quality of a molded product in an injection molding machine according to the present invention is provided in an injection molding machine in which a molded product is released from an opened mold by the ejecting means. a position detection means for detecting the moving position of the protruding part between two points, a time measuring means for measuring the moving time (detection time) of the protruding part between the respective moving positions, and a moving time corresponding to the quality of the molded product. The present invention is equipped with a reference time setting means for setting a reference time, and a comparison processing means for comparing the serious offense detection time with the reference time and outputting a comparison result, so that the following effects are achieved.

- Since the time to be detected is the movement time of the protrusion, it is possible to monitor the quality of the molded product, which is the result including all the various factors during molding, so comprehensive and accurate monitoring can be performed.

■The overall structure is simplified, making it easier to assemble, achieving significant cost reductions, and it also has excellent practicality and versatility, as it can be installed on existing molding machines.

■Since it does not affect the molding cavity or injection cylinder at all, problems such as sensor marks remaining on molded products can be eliminated.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional side view of an injection molding machine including a quality judgment device according to the present invention, Fig. 2 is a flowchart showing the functions of the quality judgment device of Fig. 1, and Fig. 3 is injection filling pressure vs. ejection force characteristics. figure. In the drawings, ■... Quality determination device for molded product, 2... Protrusion means, 3... Molded product, 4... Mold, 5... Protrusion part, 6. 7... Position Detection means, 8... Time measurement means, 9... Reference time setting means, 10... Comparison processing means, M... Injection molding machine, Pl, P2... Movement position, To... Detection Time, Tu...upper limit time (reference time'), TL...lower limit time (reference time). Figure 2 Figure 3 Injection Filling Pressure Procedure Amendment April 1985 10B

Claims (1)

[Scope of Claims] 1. In an injection molding machine in which a molded product is released from an opened mold by an ejecting means, a position detecting means for detecting a moving position between two points of a protruding part of the ejecting means; a time measuring means for measuring the moving time (detection time) of the protrusion between the respective moving positions; a reference time setting means for setting a moving time (reference time) corresponding to the quality of the molded product; A quality determination device for a molded product in an injection molding machine, comprising a comparison processing means for comparing reference times and outputting a comparison result. 2. The quality determination device for a molded product in an injection molding machine according to claim 1, wherein the reference time is set to an upper limit time and a lower limit time.