Abstract: A noise filter includes: a voltage detector which detects a common mode voltage generated by a power converter; a voltage division circuit which outputs a division voltage obtained by dividing the common mode voltage detected by the voltage detector; a plurality of common mode transformers which superimpose injection voltages each having a polarity opposite to a polarity of the common mode voltage onto an output from or an input to the power converter; and an injection waveform generator which generates, on the basis of the division voltage, output voltages to be outputted to primary sides of the plurality of common mode transformers. The injection waveform generator generates the output voltages such that a difference between the common mode voltage and a total injection voltage obtained by summing the injection voltages to be superimposed by the plurality of common mode transformers is equal to or smaller than an allowable value.

Abstract: A gas injection technique of injecting an inert gas (e.g., nitrogen gas) into a molten resin in a cavity, involves utilizing the strokes of reciprocation of a piston in the compression cylinder are used in a series mode, to perform a two-stage compression within the same cylinder, thereby providing a high-pressure gas. The method can also include establishing a relationship or pattern of the amount of movement of the piston with the speed of movement of the piston established to provide optimum control of the relationship between the pressure generated and piston stroke, and quantity of gas injected. The injecting gas pressure can be detected, to control a hold pressure, or the relationship between a piston stroke and generated pressure, so as to obtain optimal injecting pressure during the injection molding operation.

Abstract: In an automatic gas pressure welding system wherein a couple of steel members are butted, the butted section is subjected to heating in a pressed state, to thus cause the steel members to be subjected to pressure welding. The pressing and heating periods are controlled in conformity with the amount of contraction of the heated section of the steel members.

Abstract: In an automatic gas pressure welding system wherein a couple of steel members are butted, the butted section is subjected to heating in a pressed state, to thus cause the steel members to be subjected to pressure welding. The pressing and heating periods are connected in conformity with the amount of contraction of the heated section of the steel members.