Patent ID: 7329373
Filing Date: 2008-02-12
Classification: B29C

Abstract:
1. A control method of a rotational speed of a screw for an injection molding machine, wherein rotation of a motor is transmitted to the screw disposed within a cylinder member attached to an injection frame, comprising the steps of: (a) sending an electric current to a stator attached to the injection frame; (b) rotating a rotor which is disposed radially inward of the stator, the screw, and an element to be detected having a first pitch and a second pitch; (c) detecting a rotational speed of the screw by detecting the first pitch by a detecting element disposed in opposition to the element to be detected and in a manner where the detecting element does not come in contact with the element to be detected; and (d) detecting an absolute position of a first magnet attached to the rotor by detecting the second pitch different from the first pitch by the detecting element.