JPH0790352B2 - Injection control method in injection molding apparatus - Google Patents

Description

The present invention relates to a method for determining injection conditions such as injection speed in an injection molding apparatus such as a die casting machine or an injection molding machine.

[Prior Art] In recent years, in a die casting machine for injecting molten metal and an injection molding apparatus for injecting molten resin, the quality of products has been improved by controlling the injection speed and the injection pressure.

Such control of the injection speed, etc., prevents the generation and chipping of cavities by changing the injection speed or the injection pressure according to the shape and size of the product and the injection material, and by adjusting the molten metal in the cavity. Also, the product is manufactured in consideration of keeping the strength and quality of the product constant, and the injection speed is set only when high-speed injection is performed at the constant speed selected for a single product. Instead, it has been attempted to change the injection speed stepwise during the injection process depending on the shape of the product.

[Problems to be Solved by the Invention] The above-mentioned setting of the injection speed and the injection pressure often depends on experience and is determined by trial punching or the like. However, for a mold having a specific cavity shape, an appropriate injection is first performed. Determining speed was a difficult and time consuming task.

The present invention is a method for relatively easily determining the injection speed and the like.

[Means for Solving the Problem] The present invention provides a product or a wooden mold of a product manufactured by preforming, while keeping the axis of the product or the wooden mold vertical with the casting port portion downward. When the wooden mold is immersed horizontally in a container filled with a liquid and the horizontal position of the product or wooden mold is changed depending on the amount of liquid discharged from the product or wooden mold, the change in volume below the horizontal position. amount,
Then, measure the horizontal cross-sectional area of each part of the product or wooden mold with different height, set the injection conditions according to the stroke at the time of injection molding based on this cross-sectional area or volume change amount, and inject based on this condition. I will do it.

[Operation] The present invention makes it possible to easily and accurately measure the horizontal cross-sectional area of each part of the product having different heights by immersing the wooden mold or the product in a liquid, and thus to determine the horizontal cross-sectional area at each height of the cavity. You can know exactly.

Therefore, the area of the molten metal upper surface at the time of injection, and by extension, the rising speed of the molten metal upper surface corresponding to the injection speed, can be known by detecting the horizontal cross-sectional areas of the parts with different heights in the product with the casting port portion facing downward. .

In addition, by measuring the volume of a part of the product that is less than or equal to the predetermined height, the volume from the lower end of the cavity to the predetermined height of each part can be easily and accurately known, and the advance distance of the plunger tip or injection screw and the inside of the cavity can be determined. It is possible to know the relationship with the molten metal filling height.

[Embodiment] In the embodiment of the present invention, as shown in FIG. 1, the product 10 manufactured by preforming is used to measure the horizontal cross-sectional area in each part of the cavity. The mouth 13 is set downward, and the axis of the product 10 that coincides with the vertical axis of the cavity when the mold is fixed is held vertically, and in this state the product 10 is slowly immersed in a liquid such as water to The horizontal cross-sectional area is sequentially measured from the lower side.

To measure the horizontal cross-sectional area, liquid such as water is filled up to the height of the overflow outlet 16 in the container 15, and the product 10 is lowered at a constant speed so as to be immersed in the liquid fully filled in the container 15. Then, the overflowing liquid can be measured by measuring with the volume meter 19.

That is, while immersing the product 10 in the liquid at a constant speed and measuring the amount of the liquid overflowing from the container 15 by the displacement of the product 10 with the volume meter 19, as shown in FIG. (T)
Also, if a graph is created by calibrating the amount of liquid (Q) that has been rejected on the vertical axis, the time scale on the horizontal axis starts from the bottom of the product 10 because the descending speed of the product 10 is constant. The height position (h) up to the upper end of 10 is shown, and the graph shows the volume occupied by the portion of the product 10 below the height when the height is sequentially changed from below, in other words And a graph showing the volume from the lower end of the cavity to a predetermined height, and the inclination angle of this graph shows the horizontal cross-sectional area at each predetermined height position of the product or cavity. As shown in FIG. 3, the horizontal sectional area (S) at each height position (h) of the product, that is, the horizontal sectional area at each height of the cavity can be known.

Also, by measuring the amount of the overflowed liquid by weight and calculating based on this weight, the volume up to each height in the cavity can be known, and by extension, the horizontal cross-sectional area of each portion can be measured.

In this case, if the weight of the liquid that overflows when the product 10 is immersed in the liquid is measured, the
It is possible to obtain a graph having a curve with the same shape as the graph shown in the figure, and by dividing the weight by the specific gravity of the liquid and providing the scale of the required unit on the vertical axis, the volume up to the predetermined height can be easily and accurately determined. It can be measured and the horizontal cross-sectional area at each height position can be accurately obtained.

When lowering the product 10 at a constant speed, the volume up to a predetermined height and the horizontal cross-sectional area at this predetermined height can be measured by detecting the amount of liquid overflowing every unit time. Even by intermittently lowering the amount by a small amount, the horizontal cross-sectional area at each height position and the volume of the portion below the height position can be measured easily and accurately.

In this embodiment, the horizontal cross-sectional area in each part of the product 10, that is, the change in the horizontal cross-sectional area when the height in the cavity is sequentially changed in this way, is first accurately measured, and then the injection speed in the injection step. The target reference value of injection pressure is set.

That is, when the injection speed is constant, generally, the rising speed of the molten metal surface is slow in a wide horizontal sectional area, the rising speed of the molten metal surface is high in a small horizontal sectional area, and When the horizontal cross-sectional area suddenly increases from a small area, it becomes easier to entrain air by blowing out the molten metal from a small horizontal cross-sectional area. If the increase / decrease of the injection speed is determined based on the relationship with the rising speed of the molten metal upper surface in, the target reference value of the injection speed can be easily set.

Furthermore, when setting the target reference value for changing the injection speed during the injection process by changing the horizontal cross-sectional area of the cavity, the volume from the lower end of the cavity to the height of the horizontal cross-sectional area position is set together with the horizontal cross-sectional area of each part in advance. If it is to be measured, it is possible to know the advance distance of the plunger tip when the molten metal reaches the height position by this volume, and when changing the injection speed etc. according to the injection stroke, It is easy to obtain the advance position target of the plunger tip that operates.

Then, after setting the target reference values such as the injection speed in this way, if the final injection speed and injection pressure are decided by trial striking, the optimum injection speed and injection pressure according to the cavity shape, Can relatively easily determine the change points of the speed and the pressure and can set the injection condition promptly. Under this injection condition, the injection for mass production of the product will be repeated thereafter.

In the above example, the preformed product 10 is dipped in a liquid to measure the horizontal cross-sectional area of the cavity and the volume below the horizontal cross-sectional height, but it is not limited to the preformed product. The cross-sectional area and volume of the cavity can be measured in the same way by using a mold or other male mold.Furthermore, the method of determining this injection condition is not only plunger injection molding equipment such as die casting machine but also screw in-line method. The injection conditions in the synthetic resin injection molding device can be similarly set.

[Effect of the Invention] The method according to the present invention makes it possible to easily and accurately know the horizontal cross-sectional area of each part of the cavity by immersing the product or the like in a liquid and measuring the amount of the liquid to be rejected. It becomes easy to infer the speed at which the upper surface of the molten metal or molten resin rises in the cavity due to the injection speed at
Further, since it becomes easy to estimate the required injection pressure, it becomes easy to set the standard when changing the injection speed and the like during the injection process, and it is possible to quickly determine the optimum injection conditions. It is an injection control method for an injection molding apparatus capable of efficiently mass-producing high-quality and high-precision products.

[Brief description of drawings]

FIG. 1 is a diagram showing a method for measuring a cross-sectional area of a preformed product according to an embodiment of the present invention, FIG. 2 is a graph showing an example of a change in volume, and FIG. 3 is an example of a change in cross-sectional area. It is a graph which shows. 10 …… Preformed product, 13 …… Casting port, 15 …… Liquid container, 19 …… Volume meter.

Claims (1)

[Claims] 1. A product mold or a product manufactured by preforming is used, and the product mold or product is horizontally placed with the casting port of the product down, and the product or the product is prefilled from below into the liquid. By gradually measuring the amount of liquid overflowing from the container while dipping, the product occupies below the horizontal position when the horizontal cross-sectional area or horizontal position of each part of the product etc. with different height is changed. Detect each volume,
An injection molding apparatus characterized in that an injection condition corresponding to an injection stroke at the time of injection molding is set based on the changed state of the horizontal cross-sectional area or volume, and injection molding is performed based on the set injection condition. Injection control method in.