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下载后可任意编辑The question of testing mould1. Introduction Injection moulding without rejects is the ideal moulders try to attain. This article describes two auxiliary devices that could increase the repeatability of an injection moulding machine. Once the optimum parameters are set, the physical dimensions, weight and other physical properties of the part will stay almost constant. The two devices do clamping force measurement/control and cavity pressure switchover to holding pressure. For injection moulding of high precision optical parts, or parts with a high added value like appliance cases, the payoff of reduced rejects is high. Figure 1 shows the part weight distribution of quality moulding and suboptimal moulding. The nominal weight is 60 g, allowable deviation is +0.1 g and -0.05 g. The white cubes denote parts within the tolerance band. 下载后可任意编辑Figure 1. Quality injection moulding and otherwise 2. Clamping force measurement/control The clamping mechanism of injection moulding machines falls mainly into two categories: toggle and direct hydraulic. The former is more widely used; the latter has the property of automatic clamping force regulation. As a result, direct hydraulic clamp machine do not need clamping force measurement/control. 2.1 Toggle clamp A 5-point double toggle clamp is shown in Figure 2. After amplification by the toggle mechanism, the clamping cylinder, attached to the tail platen, extends, pushing the moving platen to lock the mould halves together. We 下载后可任意编辑will investigate in various ways how the clamping force is generated. Figure 2. The 5-point double toggles 2.2 Clamping force At its simplest, the rated clamping force Fo is calculated according to the following...