Plastic and nonmetallic article shaping or treating: processes – With measuring – testing – or inspecting
Patent
1992-09-09
1993-08-24
Heitbrink, Jill L.
Plastic and nonmetallic article shaping or treating: processes
With measuring, testing, or inspecting
264 404, 26432812, 425140, 425147, B29C 4576
Patent
active
052386171
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a method of monitoring the front end of flowing resin poured into a mold cavity.
2. Background Art
When setting injection conditions, there is a need for the injection speed to be determined depending on the flow resistance to which the resin passing through the cavity is subjected. The cavity has a different flow resistance for each region. For example, the flow resistance is caused to change when the resin flowing through the cavity is to be subjected to an abrupt change in the sectional area of passage due to the change in the sectional configuration of the cavity, or when the direction of the resin flow has changed extremely. Accordingly, the changeover positions of the injection speed must be set in consideration of the state of the resin to be poured into the cavity. It should be noted that the injection speed herein means a speed at which the resin is injected through a nozzle of an injection molding machine, in other words, the amount of molding material or resin to be injected into the cavity per unit time.
Conventionally, a short shot method has been used to check the state of resin filling the cavity. This short shot method comprises the steps of opening a mold after injecting a small amount of resin to check the amount of resin poured into the cavity, increasing the amount of the injected resin in sequence, finding screw positions where the flow resistance changes based on the position of the resin which has been injected into the mold, and determining the changeover position of the injection speed based on these screw positions.
In this short shot method as described above, the amount of resin must be increased a little at a time for injection, and the mold must be opened to check the position of the front end of the resin poured into the mold every time the injection is executed, which is a time and labor consuming work. Also, the short shot method may not be applied to some kind of molds, for example, for connectors. In addition, the mold may be damaged due to an excessive filling of resin in the process of searching for the injection conditions using the short shot method. This is a problem of this method.
Furthermore, it is important to determine the relationship between the state of resin injected into the cavity and the screw position, not only for determining the changeover position of the injection speed but also for providing a reference in determining the injection speed and injection pressure.
DISCLOSURE OF THE INVENTION
The object of the present invention is to provide a method of monitoring a resin position within a cavity through an automatic display of the relationship between a state of resin injected into the cavity and the screw position.
In order to achieve the above object, the first aspect of the present invention comprises the steps of:
partitioning the mold cavity into a plurality of regions with border sections where flow resistance of poured resin undergoes a great change;
setting volumes of thus partitioned regions into a control unit of an injection molding machine; and
displaying on the display unit screw positions when the leading end of the resin reaches the border sections, and a screw back position, based on a screw diameter, the amount of cushion which has been set, and said volumes of the regions, through said control unit.
Furthermore, the second aspect comprises the steps of:
partitioning the mold cavity into a plurality of regions with border sections where flow resistance of poured resin undergoes a great change;
setting volumes of thus partitioned regions into a control unit of an injection molding machine; and
displaying on the display unit screw positions at the time when the front end of the resin reaches the border sections in the cavity, based on a screw diameter, a screw back position which has been set, and said volumes of the regions, through said control unit.
Preferably, the injection molding machine is controlled by the control unit having a processor, and said volumes of the r
REFERENCES:
patent: 4832883 (1989-05-01), Kato et al.
Rosato, Dominick V., Injection Molding Handbook, 1986, pp. 98-102.
Kamiguchi Masao
Neko Noriaki
Fanuc Ltd.
Heitbrink Jill L.
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