JPS6019516A - Detecting method of life of injection head for injection molding - Google Patents

Abstract

PURPOSE:To detect the life of an injection head for injection molding by a method wherein in injection molding the operation of the stem of the injection head that has been deteriorated by seizure is detected by the operation of the working piston of the stem of the split mold. CONSTITUTION:In injection molding, when the stem 11 is free from seizure, the operation of the piston plate 13 agrees with that of the piston rod 14, but when any seizure occurs and pressure oil is supplied from the oil supply port 16a, sliding resistance increases in the stem 11, the extrusion pressure given to the piston rod 14 increases to the flange 12 and on the contrary the extrusion pressure of the flange 12 to the piston plate 13 reduces. This extrusion pressure is detected by piezo-elements 17, 18, the detected result is amplified by direct-current amplifiers 19, 20 and transferred to the control board 21. The control board 21 compares the detected result with the extrusion pressure free from seizure and if any difference between the two is detected, an alarm is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a detection method for knowing in advance the lifespan of an injection head for injection molding, particularly for use in urethane reaction injection molding (IM).

(Prior art) As shown in FIG. 1, the injection head for urethane reaction injection molding has a thin hole 2 and a wide hole 3 in the center of a head block 1.
A stem 4 is inserted into the thin hole 2, and a piston 5 attached to the stem is inserted into the thick hole 3.

A piston ring 5a for preventing leakage is provided on the outer periphery of the piston 5.
is installed. A lid 6 that closes the thick hole 3 is attached to the bottom of the head block 1 by screwing means. This lid 6 is provided with a piping attachment part 7 so that a hydraulic pressure supply piping can be attached thereto. Head block 1 111
In one song, a raw material inlet part 8 and a raw material outlet part 9 are arranged as a pair in the axial direction, and a necessary number of these pairs are provided in the circumferential direction (only one pair is shown in the figure). stem 4
A groove 10 is provided in the axial direction of the stem 4 to communicate the raw material inlet part 8 and the raw material outlet part.

The durability of this injection head is nominally 10,000 shots, but the lifespan may be shortened depending on the conditions of use. It is believed that the life of the injection head is shortened due to galling of the stem 4 on the head block 1. This becomes apparent when the injection head stops working during operation, when the stem 4 does not return and the raw material overflows, and when secondary problems occur due to backflow of the raw material, etc. Since there is no means to know the lifespan of such an injection head, it is only when a failure occurs as described above that it is known that the lifespan has reached its end.

(Object of the invention) The present invention has been made to solve the above problems.
Provides a lifespan detection method for an injection head for injection molding that detects when the stem operation during injection becomes stiff due to galling based on the operation of a split-type stem-making piston (AIJ), and detects when the lifespan of the injection head has come to an end. It is something to do.

(Structure of the Invention) A feature of the present invention is that a separation detection device is built into the stem actuating piston, which is divided into parts that can be separated from each other in the stem movement direction.
When the stem moves, the contact/disengagement detection device detects the contact/disengagement state of the stem actuating piston, compares the detection result with a prescribed reference value, and issues an alarm when the comparison result is out of the specified range. It is.

(Example) Below, one embodiment of the present invention will be explained by (>1).

As shown in FIG. 2, the stem 11 attached to the head block 1 has a flange 12 provided at the end of the entire stem of the piston section, and an injection port 1i11i of the flange 12.
The piston plate 13 that increases f and the piston rod 14V that is installed on the pressure oil injection side? It is divided into parts and assembled in such a way that the valleys can be connected to each other by l'+Ih without using any coupling means such as screw parts. An H through hole 15 is opened in the center of the piston rod 14 and arranged ii! J! Make it possible to pass through. Leak-preventing piston rings 13.11 and 148 are attached to the outermost peripheries of the piston plate 13 and piston rod 14. A hole through which the piston rod 14 passes and an oil supply hole 16a
Attach the metal fitting lζ lid 16 to the pressure oil injection hole 1 of the head block 1.

The injection port side of the flange 12 provided on the stem 11 and the pressure inlet (the piezoelectric elements 17 and 18 are glued to the till), and the pressure in between the piston plate 13 and the flange 12 is attached to the piezoelectric element 17. The piezoelectric element 18 detects the crimp load sound between the flange 12 and the piston rod 14.The piezoelectric elements 17 and 18 are wired using two lines of wiring connected to the piston rod 14 from the outside. ¥1
One system is connected to the piezoelectric element 18 through the through hole 15 to the stem surface of the piston rod 14, and the other system is connected to the piston plate of the flange 12 by drilling five holes 12a through 12a for wiring in the flange 12. Contact (output to Jji and connect to piezoelectric element 17. Wiring for the two systems is connected to head block 1
Each is connected to a DC amplifier 19, 20 externally, and one DC amplifier.

20 to the control panel 21.

During injection molding, if the stem 11 does not bend, the piston plate 13 and piston rod 14
0 crops are consistent, but if galling occurs, the oil supply port 16a
When pressure oil is supplied from the piston plate 13, the sliding resistance of the stem 11 increases, and the pressing force applied to the piston rod 14 increases against the flange 12, and conversely, the pressing force from the flange 12 to the piston plate 13 decreases. do. This pressing force is detected by piezoelectric elements 17 and 18, and the detection results are amplified by DC amplifiers 19 and 20 and transmitted to control panel 21. Control panel 2
In 1, the detection results for the pressing force in the case of no galling are compared, and if there is a difference, an alarm is issued to notify the operator. The return motion of the stem 11 can also be obtained by reversing the direction of motion and the relationship between the piezoelectric elements 17 and 18.

In this manner, the lifetime of the injection head is determined based on the detection results from the pressure 11i elements 17, 18 when an abnormality occurs in the operation of the stem 11, thereby making it possible to detect it before a failure occurs. This makes it possible to prevent secondary problems such as the injection head not working during production, the stem 11 not returning and the raw material overflowing, and the occurrence of secondary problems due to backflow of the raw material. Become.

In the above embodiment, the piston ring i4a is provided on the outermost circumference of the piston rod 14, but it may not be provided if the degree of fitting is good. Stem 11 instead of piezoelectric element 16 and 17
A strain gauge may be used to measure the axial displacement of.

(Effects of the Invention) According to the above-described method for detecting the life of an injection molding head according to the present invention, it becomes possible to detect the entire life of the injection head at ai1. This makes it possible to prevent accidents during production and improve the operating rate of the injection molding machine.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a conventional injection molding injection head, and FIG. 2 is a longitudinal cross-sectional explanatory view of an injection molding injection head according to the present invention. 1...Head block 11...Ste 11 12...Flange 13...Piston plate 14...Piston rond 16...Lid 17.18...Piezoelectric element 19.20...DC amplifier 21... Control panel patent applicant Toyota Motor Corporation

Claims (1)

[Scope of Claims] (11) A stem actuating piston that is movable toward and away from the stem movement direction has a built-in separation detection device, and when the stem moves, the stem actuation piston Detects the state of disengagement, compares the detection result with the specified standard value, and if the comparison result is outside the specified range, the answer is ￥K
A method for detecting the life of an injection head for injection molding, which is characterized by emitting .