Development of barrel heating system in injection molding machine via induction heating

Abstract

Purpose -The purpose of this paper is to develop a barrel heating system using induction heating instead of resistance heating. And, a working coil for the induction heating system was designed so that the barrel has uniform temperature distribution. Design/methodology/approach -A coupling design combining the pitch of turns of working coil with the magnetic flux concentrators in the barrel induction heating system was developed to achieve uniform temperature distribution which was approximately the same as temperature uniformity obtained from that of resistance heating system. Findings -In contrast to resistance heating method, induction heating is more efficient because the heating is directly applied on the work-piece. Its heating rate is higher than that of resistance heating method. However, the uneven temperature distribution in the barrel is the main disadvantage of the induction heating system. But, with proper design of adjusting the pitch of turns at the center of working coil and adding magnetic flux concentrators at areas with lower magnetic flux, the barrel heating system via induction can achieve temperature distribution uniformity. Originality/value -Under proper design of working coil, the barrel heating system by induction method can achieve the same uniform temperature distribution as the barrel heated by resistance method, and could be practically used in an injection molding machine.

A Study of Induction Hardening Parameters for the DIN 42CrMo4 Alloy through Its Microhardness, Corrosion Resistance, and Microstructure Examination

“…Therefore, a preliminary study was conducted to calculate the current penetration into the metal, in order to model the parameter for complete heat penetration and to receive a through thickness response of the selected alloy. In the induction hardening process, current penetration is a function of material's property and the induction parameters which were determined from the procedures mentioned in the literature [2,18,19].…”

Design of an induction heating coil coupled with magnetic flux concentrators for barrel heating of an injection molding machine

“…5,6 In addition, magnetic flux tends to concentrate toward the center of the length of a working coil, and thus the heating rate in this area is generally higher than that produced toward the end sides of working coil. 7 However, in an injection molding machine, uniform temperature distribution along the heated part on the surface inside the barrel is required. This is the main drawback of IH system when applied in an injection molding machine.…”

“…This is the main drawback of IH system when applied in an injection molding machine. There are several approaches to modify the magnetic flux field or uniform temperature distribution such as adjusting the number of turns in a working coil, adjusting the pitch of turns of working coil, 7,8 adjusting the distance between coils and barrel, 9,10 changing cross-section shape of coil, 11 using magnetic concentration bars, 7 and so on.…”

“…Although uniform temperature distribution is achievable with coil modification and adjustment, the process is tedious and time consuming. 7 This drawback is one of the reasons why induction heating of barrel is not popular. To solve this problem, an induction heating coil coupled with magnetic flux concentrators was proposed.…”

Modeling of the Injection Molding Process Coupled with the Fast Mold Temperature Evolution

“…They may be classified into two main categories: 1) the control of the temperature evolution of the whole mold, or of a large part of it; 18 2) the local control of the cavity surface temperature. 19 The first category includes the use of heating/cooling fluids in the mold channels, [20][21][22][23] the induction heating, [24][25][26][27] and the infrared heating. 2,[28][29][30] The second category includes the use of all devices that allow limiting the heating stage to the cavity surface, such as the proximity heating 31,32 and the electrical heating of the cavity surface.…”