Plastic and nonmetallic article shaping or treating: processes – With measuring – testing – or inspecting
Patent
1993-01-14
1994-03-22
Thurlow, Jeffery
Plastic and nonmetallic article shaping or treating: processes
With measuring, testing, or inspecting
364476, 425145, 425149, 264 405, B29C 4576
Patent
active
052961796
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to an injection molding machine having a screw for filling a resin into a mold cavity and controlled by, for example, numerical control, more particularly to an injection pressure monitoring method for simplifying the setting of molding conditions for injection molding and an apparatus for practicing the method.
2. Background Art
An injection molding machine is intended to mold products by injecting a resin material into a mold cavity using a screw. In general, the injection molding machine has a multistep injection speed control for changing the injection speed for various levels in response to a screw position. The injection speed must be set in consideration of the flow resistance of a resin, because the flow resistance varies depending on the regions through which the resin passes. Therefore, for the determination of the injection speed and a changeover position of the injection speed, the screw position corresponding to the state of resin being filled into the mold cavity must be properly grasped.
Conventionally, the short shot method has been used as a way of checking the state of resin being filled into the cavity. This short shot method comprises the steps of opening a mold after a small amount of injection of resin to check the amount of resin filled into the cavity, increasing the amount of the injected resin in sequence, finding screw positions where the flow resistance undergoes a change based on the resin position which has been filled into the mold, and determining the changeover position of the injection speed based on these screw positions.
As described above, in the short shot method, the amount of resin injected must be increased little by little, and the mold must be opened to check the position of the leading end of the resin filled into the mold every time the injection is executed, which is a time-and-labor-consuming work. Besides, the short shot method may not be applicable to some kind of molds, for example, for connectors, because the practicing of the short shot causes a part of the molded product to be left within such mold which may damage the mold. Furthermore, the practicing of the short shot may possibly prevent the molded product from being taken out of a type of mold. Moreover, an overfilling of the resin may disadvantageously take place (irrespective of the mold to be used) during the progress of the setting of the molding conditions by the short shot method.
DISCLOSURE OF THE INVENTION
It is therefore the object of the present invention to provide a method and an apparatus for monitoring an injection pressure capable of easily performing, for example, setting of injection conditions or change of the set injection conditions in view of positions where a resin within a cavity undergoes a change in flow resistance, by providing the operator with the graphically presented information concerning the relationship between an injection pressure and a screw position, a state of the resin being filled into the cavity and a position of the screw corresponding to the state, by way of the display of the injection pressure as well as a picture of the cavity on a display screen.
In order to achieve the above object, according to the first aspect of the present invention, a method of monitoring injection pressure applicable to an injection molding machine having a screw adapted to be propelled to fill a resin into a cavity of a mold comprises the steps of: storing in advance cavity data of the mold; displaying, based on the cavity data, a configuration of the cavity and divided regions obtained by dividing the cavity into a plurality of regions in a cavity display section provided on a display screen; detecting a screw position by a screw position detecting means while detecting an injection pressure at the screw position by a pressure detecting means; displaying in a graph a relationship between detected screw position and injection pressure in a pressure waveform display section provided on the display screen; and display
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Kamiguchi Masao
Neko Noriaki
Fanuc Ltd.
Thurlow Jeffery
Vargot Mathieu
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