The matching precision of mold deep hole processing is one of the key factors determining the heating effect and service life of limit-type single-end electric heating tubes. This type of high-precision heating tube has strict requirements on the tolerance of the mold mounting hole. Unreasonable hole processing technology and insufficient precision will lead to poor fitting degree between the heating tube and the mold, resulting in poor heat dissipation, uneven temperature and frequent equipment failure. Therefore, mold hole processing must follow standardized precision standards to ensure the best matching state of the heating tube and the mold.
In mold processing, the most common error is the double-ended drilling process. Many processing personnel adopt the method of drilling from both ends of the mold to save processing time. However, this processing method has an unavoidable technical defect: the joint of the two drilling holes cannot be completely closed and fitted, forming obvious gaps and voids. These tiny pores will form a heat insulation layer between the outer wall of the heating tube and the inner wall of the mold hole, which seriously hinders the rapid conduction of heat.
The gap heat insulation problem caused by double-ended drilling will bring dual losses to production. On the one hand, the heat generated by the heating tube cannot be quickly transferred to the mold body, resulting in a large amount of heat accumulated on the tube wall, causing local overheating and scorching blackening of the heating tube, accelerating the aging and damage of the heating element. On the other hand, the uneven heat conduction makes the temperature of each area of the mold inconsistent, resulting in local high temperature and local low temperature in the mold cavity, which seriously affects the forming accuracy of plastic products, die-casting parts and injection molding products, and leads to defective products.
The standard processing specification is to adopt single-ended one-time drilling and forming process. The single-sided drilling technology ensures that the inner wall of the mold hole is smooth and flat, the hole diameter is uniform without staggered joints, and the inner wall of the hole is completely fitted with the outer circle of the heating tube. The seamless fitting structure realizes rapid and uniform heat conduction, ensures that the heat of the heating tube is fully transferred to the mold, avoids heat accumulation of the tube body, and realizes uniform overall temperature of the mold.
In addition to the processing technology, the hole diameter tolerance must be strictly controlled. The limit-type single-end heating tube has high outer diameter precision, and the matching mold hole needs to control the error within a small tolerance range. Too large aperture will cause gaps, and too small aperture will cause difficult installation and tube body extrusion deformation. Strict mold precision processing is the basic guarantee for the heating uniformity of the heating tube and the stability of long-term operation, and is a necessary link in the installation and use of high-precision heating tubes.
