VECTORFORM LIFTER SYSTEMS Ordering Information
VECTORFORM LIFTER SYSTEMS Dual-Rod Design Benefits
A New Approach to Designing Lifter Cores: Dual-Rod Design
VectorForm Lifter Set Ordering Information
Benefits of using a secondary guide rod on lifter core assemblies Conventional lifter cores have been somewhat limited in their performance given the large mold foot-prints they create. Reactionary forces and bending moments within conventional lifter core rods require smaller rod angles, which can increase mold die height and footprint. A new approach to designing lifter cores utilizes a second guide rod that is parallel to the lifter rod. This formation eliminates the bending moment seen in conventional single-rod lifter configurations, allowing for a greater lifter angle and reducing overall die height and mold footprint. Single-Rod Lifter Systems When designing mold cores for undercuts and side-action molding, the designer has several lifter system options. The first is using sliding cores and angle pins. This option requires considerable mold space and may result in selecting a lifting core with a smaller platen size at the expense of a larger die height. Conventional lifter cores also have limits on the angles allowed. If the molded undercut is large, the mold footprint may need to be increased to accommodate the required side travel of the lifter core, increasing the required die height even further. The single-rod lifter system is designed with the core, sliding plate and gib plates within the ejector plate assembly. Close alignment of the core is accomplished through tight tolerance entrance and exit holes in the core plate. This results in additional cost and added processing problems. An overriding problem of the conventional configuration: bending moment acting on the lifter rod, which leads to increased friction, abrasion and side loads. If the lifter rod is not sized properly, premature wear or even breakage can result. Therefore, designers often over-design the lifter rod to account for additional loading. This increases component costs and limits the number of applications for the lifter mechanism. Dual-Rod Lifter Systems Use of a second guide rod parallel to the lifter core is a relatively new and under-utilized method. The additional guide rod ensures proper alignment of the sliding base within the ejector plates. It also eliminates the bending stresses that occur as a result of the typical load distribution described within the conventional setup. The new configuration creates a parallelogram within the ejector plate assembly between the primary lifter core, secondary alignment rod, alignment plate and sliding alignment base, as shown in Fig. 1 . The structurally sound parallelogram eliminates the bending moment that occurs in single-rod systems. Mold designers should note that the strength of the assembly will be that of the weakest link. The use of a fixed secondary pin eliminates friction between the secondary pin and the upper alignment plate. The actuating load transferred to the primary lifter core is now centered on the axis of the lifter core and in the same direction as the motion of the core. The reduction in friction and bending moment permits a greater lifter angle, allowing the designer to reduce both the necessary die height and the mold footprint on the platen (see Fig. 2 ).
SIZES
06
08
10
13
16
20
SS – STANDARD SET
VF06SS VF06JS VF06US
VF08SS VF08JS VF08US
VF10SS VF10JS VF10US
VF13SS VF13JS VF13US
VF16SS VF16JS VF16US
VF20SS VF20JS VF20US
JS – JOINT SET
US – UNIVERSAL SET
VectorForm Lifter Sets include: (1) Holder Bushing – HB
(1) Guide Rod – GR (1) Guide Plate – GP (1) Slide Base (Standard – SB, Joint – JB, or Universal – UB)
Fig. 1 Example of a preferred embodiment for designing a lifter core assembly. A second guide rod is used to create a parallelogram that significantly reduces moments acting on the lifter rod.
Fig. 2 Reduction in bending stress in lifter rod allows for larger angle, thereby reducing die height.
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U.S. 800-626-6653 ■ Canada 800-387-6600 ■ dme@milacron.com ■ www.dme.net ■ store.dme.net
U.S. 800-626-6653 ■ Canada 800-387-6600 ■ www.dme.net ■ store.dme.net
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