Injection molding apparatus and mold clamping device

An injection molding apparatus configured to perform injection molding of a molded article using a molding die configured with a fixed mold and a movable mold, the apparatus comprising:

• an injection unit configured to inject a material of the molded article into the molding die;
• a mold clamping unit to which the molding die is attached and which is configured to perform mold clamping of the molding die;
• and
• a controller configured to control the injection unit and the mold clamping unit, wherein
• the mold clamping unit includes
• a toggle fixing portion,
• a fixed mold attachment portion to which the fixed mold is attached,
• a movable mold attachment portion which is disposed between the toggle fixing portion and the fixed mold attachment portion so as to be movable forward and backward in a mold clamping direction, and to which the movable mold is attached,
• a motor,
• a ball screw attached to the toggle fixing portion and configured to rotate due to driving of the motor,
• a crosshead configured to move between the toggle fixing portion and the movable mold attachment portion due to rotation of the ball screw, and
• a toggle section coupled to the toggle fixing portion, the movable mold attachment portion, and the crosshead and configured to move the movable mold attachment portion along the mold clamping direction due to a movement of the crosshead,
• the toggle section includes
• a first member coupled to the toggle fixing portion via a first rotary shaft,
• a second member coupled to the first member via a second rotary shaft, and coupled to the movable mold attachment portion via a third rotary shaft, and
• a third member coupled to the crosshead and coupled to the first member via a fourth rotary shaft, and
• a length of a line connecting a center of the first rotary shaft and a center of the second rotary shaft in the first member is equal to or longer than a length of a line connecting a center of the second rotary shaft and a center of the third rotary shaft in the second member.