Band heater clamp arrangement for an injection molding machine

An injection molding machine including a hot-runner structure having a channel for conveying liquified plastic material to an injection gate of a mold plate, said molding machine comprising:

• a tubular body formed from a material having a good thermal conductivity forming a part of said channel and heater means surrounding a portion of said tubular body for maintaining plastic material in a liquified state within said part of said channel formed by said tubular body;
• said heater means comprising a heater sheath and a heater coil located within a cavity formed in said heater sheath;
• said heater sheath comprising a coaxial tube assembly having a bimetallic construction;
• said heater sheath having an inner sleeve formed from a material having a first thermal expansion and an outer sleeve formed from a material having a second thermal expansion;
• and
• said inner sleeve having a longitudinal axis and at least one axial slot which extends substantially parallel to said longitudinal axis, said at least one axial slot redirecting radial forces generated by said inner sleeve into circumferential forces so as to obtain clamping of said heater sheath to said tubular body.

An improved heater-clamp arrangement for use in an injection molding machine, said heater-clamp arrangement comprising:

• a cylindrical body having a cylindrical inner sleeve and a cylindrical outer sleeve;
• said inner sleeve being formed from a different material than said outer sleeve;
• said inner sleeve being formed from a material having a first thermal expansion;
• said outer sleeve being formed from a material having a second thermal expansion, said first thermal expansion being greater than said second thermal expansion so that said inner sleeve expands more than said outer sleeve when said sleeves are heated;
• a heater coil positioned within at least one space, said space being machined into said inner sleeve and being located between a first surface of said inner sleeve and an inner surface of said outer sleeve;and
• said greater expansion of said inner sleeve creating a desired clamping force.

An improved heater-clamp arrangement for use in an injection molding machine, said heater-clamp arrangement comprising:

• a cylindrical body having a cylindrical inner sleeve and a cylindrical outer sleeve;
• said inner sleeve being formed from a material having a first thermal expansion;
• said outer sleeve being formed from a material having a second thermal expansion;
• a heater coil positioned between a first surface of said inner sleeve and an inner surface of said outer sleeve and
• said inner sleeve having an axial slot which extends along the length of the inner sleeve, said axial slot redirecting radial forces generated in said inner sleeve during heating into circumferential clamping forces for enabling clamping of said heater-clamp arrangement to another body.

An improved heater-clamp arrangement comprising:

• a cylindrical heater sheath;
• a heating coil positioned within said sheath;
• said heater sheath being formed by a cylindrical inner sleeve and a cylindrical outer sleeve;
• and
• said cylindrical inner sleeve having an axially extending slot which redirects radial forces generated in said inner sleeve during heating into circumferential clamping forces.