Method for designing a resin product, method for producing a resin product and injection molding device

A method for obtaining resin product design parameters for use in an event of designing a resin product to be molded by injection molding, the method comprising the steps of:

• obtaining a mold clamping force required for conducting injection molding of a resin product having a specified shape using a computer-aided optimization method;
• and obtaining the design of said resin product based on the thus obtained mold clamping force, and
• in which a process parameter for determining an inflow of a resin material from a plurality of resin inflow conduits connecting with a cavity is used as a variable parameter for determining said mold clamping force,
• wherein said process parameter is a parameter which controls actions of valve gates located at said plurality of resin inflow conduits, and
• wherein resin product design parameters are optimized under the condition where at least one of the valve gates is selected as a timing regulation gate that is restricted by the action of other gates, in order that at least one valve gate is kept open at any given time during filling stage.