AU2012100839B4 - Injection Moulded Lightweight Components - Google Patents

Abstract

A method of injection moulding synthetic plastic components that have portions with a rear non display face that is substantially flat in which a pattern of recesses is created in the rear face. The depth of the recesses is up to 35% of the thickness of s the component and the recesses comprise from 30% to 75% of the rear face. This provides a weight reduction of about 25% compared to conventional tooling without any reduction in the functional characteristics or strength of the panel. The reduced mass contributes to a reduced primary power consumption and carbon dioxide emission of up to 25% per Kg of moulded product.

Description

1 INJECTION MOULDED LIGHTWEIGHT COMPONENTS This invention relates to a method of injection moulding components for vehicles to reduce the weight and carbon footprint associated with the components. 5 Background to the invention It is common to make many panels and components from polymeric materials. These components are cost effective for use in vehicle both interior and exterior and in aircraft cabins. Current design techniques used by the Australian vehicle supply industry is based on dated tooling methods and focus on strength rather than mass 10 reduction. Government and consumer concerns have encouraged the vehicle industry to seek ways reduce carbon emissions and improve fuel economy. In order to improve the performance of vehicles the weight of the vehicle has been targeted for reduction to improve the power to weight ratio. This has a limit in that 15 the structural characteristics of the components need to be retained. However there is now a demand for reducing the mass of all plastic components It is object of this invention to provide a technique for reducing the weight of some plastic components. 20 Brief description of the invention To this end the present invention provides a method of injection moulding synthetic plastic components that have portions with a rear non display face that is substantially flat in which a pattern of recesses is created in the said face in which the depth of the recesses is up to 35% of the thickness of the component and the 25 recesses comprise from 30% to 75% of the said face. The recesses may be of any suitable shape such as circular or square, however hexagonal recesses are preferred. By using recesses the structural integrity of the component is not compromised. To injection mould such parts the die must include a complementary shaped tool. The shape of the tool needs to take into account the 30 flow characteristic of the polymer injected into the mould. In another aspect this invention provides a vehicle part made of injection moulding synthetic plastic that has a portion with a rear non display face that is substantially flat in which a pattern of recesses is created in the said face in which the depth of 2 the recesses is up to 35% of the thickness of the component and the recesses comprise from 30% to 75% of the said face. Detailed description of the invention 5 A preferred embodiment of the invention will now be described with reference to the drawings in which : Figure 1 shows an edge cross section of a flat panel; Figure 2 illustrates a rear surface recess pattern in accordance with the invention; Figure 3 is a front view of a vehicle number plate bracket in accordance with this 10 invention; Figure 4 is a rear view of the vehicle number plate bracket of figure 3; Figure 5 is a cross section of figure 4 along the line A -A. Figure 1 illustrates an injection moulded panel in which the rear surface (top) is 15 recessed with hexagonal recesses as shown in figure 2. The depth of the recesses is 35 % of the thickness of the panel. The vehicle number plate as shown in figures 3 to 5 has a front face 11, and a rear face 12 and side walls 13 and 14. The fastening holes 15 are conventional. On the rear surface 12 the hexagonal pattern of recesses 16 as illustrated in figure 2 has 20 been applied to reduce the wall thickness by 15.5%. This provides a weight reduction of up to 25% compared to conventional tooling without any reduction in the functional characteristics or strength of the panel. The injection moulding tools for the component are micro cored using an hexagonal ribbing pattern to create high flow channels and controlled voids on the rear face of 25 plastic components to reduce mass whilst maintaining rigidity. Other shaped recesses may be used but the hexagonal shape provides a maximum area for recessing compared tother shapes. Less material is required to form the component and this cost saving off sets the cost of the tooling required. The reduction in material used also contributes to cost 30 reduction because of a reduced cycle time for the injection moulding operation. The reduced mass contributes to a reduced primary power consumption and carbon dioxide emission of up to 25% per Kg of moulded product.

3 From the above it can be seen that this invention provides a unique means of providing a cost effective means of reducing carbon dioxide emissions without compromising vehicle performance. Those skilled in the art will realise that this invention may be applied to plastic vehicle components other than those described 5 without departing from the core teachings of this invention.

Claims (1)

1. 2. A vehicle part as claimed in claim 1 in which the recesses are hexagonal . 15