JPH0275460A - Pressure timing control method for pressure pin - Google Patents

Abstract

PURPOSE:To exactly execute the protrusion control of a pressure pin by measuring a pressure stroke of the pressure pin at every shot, operating a pressure timing which can secure a necessary pressure stroke from its measured value and controlling the subsequent pressure operation of the pressure pin. CONSTITUTION:After filling of molten metal, hydraulic pressure is supplied to a pressure cylinder 5 from a hydraulic valve 6 by a timing obtained in advance by a conventional experience, and by operating the hydraulic cylinder 5, a pressure pin 4 is protruded into a cavity 3. The molten metal becomes a filling state having no clearance, and a satisfactory cast product is obtained. Subsequently, a stroke of the pressure pin 4 by which the product becomes the most satisfactory state is obtained, and an output signal of a potentiometer 9 at that time is inputted to a microcomputer 10. The computer 10 measures a pressure stroke from its value, determines an optimum timing in the next shot, and feeds it back to the next shot.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for controlling the pressurizing timing of a pressurizing pin, which improves the pressurizing timing setting of the pressurizing pin in the casting process of die-casting. be.

(Prior Art) When manufacturing a die-casting, when the molten metal injected into the cavity is cooled and solidified, its volume contracts, which causes indentation within the cavity. These defects impair the finished shape of die-cast products,
Alternatively, oil leakage may occur, which may impede the performance of the product. Therefore, conventional measures have been taken to prevent this. The most common method for this is
This is a method in which a pressure pin is provided in the vicinity of the cavity, and the pressure pin is projected into the cavity immediately before the molten metal poured into the cavity solidifies. Publication No. and Japanese Unexamined Patent Publication No. 5
8-9758).

(5! Problem to be solved by Ming) Among the above methods of pressurizing the molten metal just before solidification by protruding the pressure pin into the cavity, the technique described in the former publication is The technology described in the latter publication uses a sensor to detect the temperature of the mold or the temperature of the molten metal in the cavity, and control is performed based on this detected temperature. be. In the former technology, the solidification rate differs between before the mold temperature rises at the start of casting and when the mold temperature stabilizes, and between summer and winter, so the timing of pressurization changes, which can cause variations in product quality. There was a problem. On the other hand, the latter technique has a problem in that it is difficult to understand the relationship between mold temperature or molten metal temperature and pressurization timing unless a considerable amount of data is accumulated. Furthermore, variations in the mold temperature, molten metal temperature, and pressurizing effect tend to occur, and because these elements do not correspond to each other, there is a problem that even if controlled, it is not very effective in improving quality. .

The present invention has been made with the aim of solving these problems of the above-mentioned prior art, and by calculating the pressurizing timing that can ensure the necessary pressurizing stroke of the pressurizing pin, it is possible to always The purpose is to provide a method that allows you to obtain products of good quality.

(Means for Solving the rlA Problem) As a means for solving the above problems, the present invention provides a die casting method in which a pressure pin is pushed into a die casting immediately before solidification, in which the pressure stroke of the pressure pin is changed every time. The method is characterized in that a shot is measured, a pressurizing timing that can secure a necessary pressurizing stroke is calculated from the measured value, and subsequent pressurizing operations of the pressurizing pin are controlled by the pressurizing timing. This method of the invention can be implemented on a microcomputer by programming a predetermined program.

(Function) The method of the present invention having the above configuration calculates data for each shot and obtains the pressurization timing in the subsequent die-casting process from that value, so that die-cast products of constant quality can be stably obtained at all times. It turns out.

(Example) Next, a method for controlling the pressurizing timing of a pressurizing pin according to the present invention will be described with reference to the drawings. In FIG. 1, 1.2 is a die-casting mold, and 3 is a cavity formed therebetween. A pressure pin 4 is provided inside one of the die-casting molds 2, facing the cavity 3, and is adapted to project into and retreat into the cavity 3 by a pressure cylinder 5. A hydraulic valve 6 is connected to the pressure cylinder 5, and the movement of the pressure pin 4 is controlled by the flow of hydraulic oil between the hydraulic pressure source 7 and the drain tank 8.

A potentiometer 9 is attached to the rear part of the pressure cylinder 5, and is coupled to a cylinder rod (not shown) inside the pressure cylinder 5, and is connected to a cylinder rod (not shown) inside the pressure cylinder 5, and controls its stroke, that is, the pressure pin 4.
The stroke is converted into an electrical output signal. The output side of the potentiometer 9 is connected to the microcomputer 1O, so that the pressurization stroke can be read. The microcomputer IO measures the pressurizing stroke, determines the optimal timing for the next chute, and issues a control signal to the hydraulic valve 6 that operates on the next chute.

To carry out the method of the present invention using the apparatus prepared in this way, the following procedure is performed. First, the die casting mold 1.2 is closed to form a cavity 3, and this cavity 3 is rapidly filled with molten metal. The molten metal from this time will be used as a dummy. After filling the molten metal, hydraulic pressure is supplied from the hydraulic valve 5 to the pressurizing cylinder 6, and the pressurizing cylinder 5 is operated and pressurized at a timing that has been obtained in advance through conventional experience, or after an appropriately determined period of time has elapsed. The pressure pin 4 is made to protrude into the cavity 3. As the pressure pin 4 protrudes, the volume inside the cavity 3 is reduced, so that the molten metal forms a packed layer with no gaps, resulting in a good quality cast product. At this stage, the stroke of the pressure pin 4 is checked so that the product is in the best condition.

In this way, the stroke of the pressure pin 4 that brings the product into the best condition is obtained, and the output signal of the potentiometer 9 at that time is taken into the microcomputer IO.The microcomputer IO applies pressure based on the taken value. It measures the pressure stroke, determines the optimal timing for the next shot, and feeds it back to the next shot. Steps 11 to 16 in FIG. 2 are a flowchart showing the above procedure. Also the third
The figure shows the correlation between the pressurization stroke and the leak defect rate, and FIG. 4 shows the correlation between the pressurization stroke and the pressurization timing. The conditions for the maximum pressure stroke in FIG. 3 are from the maximum value when the pressure timing is 0 in FIG. 4 to the value indicated by the sign when 10 seconds have elapsed.

When the method of the present invention was actually used to control the pressure timing of the pressure pin, it was found that the defect rate and variation in two different parts of a certain product were significantly different from those obtained using the conventional method. was completed. In other words, while the conventional leak failure rate at one location was 3.8%, it was 1.9% with the method of the present invention, and the variation was 2.2% in the conventional method. Whereas,
Those obtained by the method of the present invention decreased by 1.6%. In addition, the conventional leak defect rate in other parts is 11.4.
%, whereas it was 3.9% for the method of the present invention, and the variation was 2.4%, compared to 4.1%. As a result, the lead time, which is the period from one order to delivery by nine people, has been significantly improved. By the way, if you install 10 pressure pins, the conventional ones will cost 3 to 41!
1 month, whereas the method of the present invention requires 2R
A few days was sufficient.

The reason why such excellent results can be obtained is that the method of the present invention is a control method that has a learning function, so that the effort required to set the conditions for pressurization timing can be significantly reduced. Because I was able to do it.

In the embodiment described above, a potentiometer was used to measure the pressurizing stroke of the pressurizing pin, but this measurement in the method of the present invention is not limited to this, and other measuring means such as an encoder etc. In short, any type can be used as long as it can accurately measure the movement stroke of the pressure pin. Further, the feedback to the next shot is not limited to the feedback from the previous shot, but a method may be used in which the timing of the next shot is determined based on the pressurizing strokes of a plurality of past shots.

(Effects of the Invention) Since the present invention is a method for controlling the pressurizing timing of the pressurizing pin configured as described above, it is possible to accurately control the protrusion of the pressurizing pin without requiring any skill. This has the effect of making it possible to

[Brief explanation of the drawing]

FIG. 1 is a system diagram partially showing a cross section of equipment for realizing the method of the present invention, FIG. 2 is a flowchart, and FIGS. 3 and 4 are graphs showing the effects of the method of the present invention. L, 2 - Die casting mold 3 - Cavity 4 - Pressure pin 5 - Pressure cylinder 9 - Potentiometer 10 - Microcomputer patent Applicant Toyota Motor Corporation Fig. 1 4 JD, ff Bishi 5・Pressure resin 9 ・Potentiometer 10 Microcosobulator

Claims (1)

[Claims] (1) In the die-casting method in which a pressure pin is pushed into the die-casting just before solidification, the pressure stroke of the pressure pin is measured every shot, and from this measurement value the pressure timing that can ensure the required pressure stroke is calculated. A method for controlling the pressurizing timing of a pressurizing pin, characterized in that a subsequent pressurizing operation of the pressurizing pin is controlled by the pressurizing timing.