Mold clamping force setting device and mold clamping force setting method of injection molding machine

摘要

A distortion sensor is provided on each of a plurality of tie bars and the extension amount of each tie bar is detected by the distortion sensor thereof, whereby a mold clamping force actually applied to a mold is measured. This measurement specifies the part of the mold that first opens and obtains a minimum mold clamping force that does not open the mold in that part. The minimum mold clamping force thus obtained is the minimum mold clamping force that does not open the mold without being influenced by factors such as the shape and the arrangement of a cavity in the mold and the mold clamping force balance of a mold clamping part of an injection molding machine.

主权项

1. A mold clamping force setting device of an injection molding machine, the injection molding machine including a mold clamping part that closes a mold based on a set mold clamping force to generate a mold clamping force and an injection part that injects molten resin into the mold, the mold clamping force setting device comprising:
a plurality of mold clamping force detecting parts configured to detect mold clamping forces in different positions on the mold clamping part; a maximum mold clamping force increase amount calculation part configured to perform injection with an optional set mold clamping force and obtain a maximum mold clamping force increase amount being the difference between the mold clamping forces, generated when the mold is closed, that have been detected by the mold clamping force detecting parts and a maximum mold clamping force value during injection, generated when molten resin is injected into the mold, for each of the mold clamping force detecting parts; a storing part configured to store therein mold clamping forces generated when the mold is closed and the corresponding maximum mold clamping force increase amounts, for each of the mold clamping force detecting parts; an extracting part configured to extract two or more pairs of the set mold clamping force and the maximum mold clamping force increase amount that are different in maximum mold clamping force increase amount and have a set mold clamping forces not enough to open the mold, in at least one of the mold clamping force detecting parts; a relational expression calculation part configured to, for the mold clamping force detecting part for which the two or more pairs of the set mold clamping force and the maximum mold clamping force increase amount are extracted by the extracting part, obtain a relational expression indicating a maximum mold clamping force increase amount with respect to a set mold clamping force from the two or more pairs as a relational expression of the mold clamping force detecting part; a mold clamping force calculation part configured to, for the mold clamping force detecting parts for which the relational expressions therefore are obtained by the relational expression calculation part, out of the plurality of mold clamping force detecting parts, perform injection with a set mold clamping force smaller than the set mold clamping forces included in the two or more pairs, extracted in association with the mold clamping force detecting part, calculate the maximum mold clamping force increase amount, and obtain a set clamping force when the maximum mold clamping force increase amount exceeds a predetermined threshold determined based on the relational expression of the mold clamping force detecting part; and a mold clamping force setting part configured to set a set mold clamping force immediately before the set mold clamping force obtained by the mold clamping force calculation part to a required minimum mold clamping force that does not open the mold.