Topic
Core drill
About: Core drill is a research topic. Over the lifetime, 870 publications have been published within this topic receiving 4867 citations.
Papers published on a yearly basis
1 / 2
Papers
TL;DR: In this paper, the authors examined the theoretical predictions of critical thrust force at the onset of delamination, and compared the effects of different drill bits, including saw drill, candle stick drill, core drill and step drill.
Abstract: Drilling is the most frequently employed operation of secondary machining for fiber-reinforced materials owing to the need for joining structures Delamination is among the serious concerns during drilling Practical experience proves the advantage of using such special drills as saw drill, candle stick drill, core drill and step drill The experimental investigation described in this paper examines the theoretical predictions of critical thrust force at the onset of delamination, and compares the effects of these different drill bits The results confirm the analytical findings and are consistent with the industrial experience Ultrasonic scanning is used to evaluate the extent of drilling-induced delamination The advantage of these special drills is illustrated mathematically as well as experimentally, that their thrust force is distributed toward the drill periphery instead of being concentrated at the center The allowable feed rate without causing delamination is also increased The analysis can be extended to examine the effects of other future innovative drill bits
430 citations
TL;DR: In this article, the critical thrust force at the onset of delamination is predicted and compared with the twist drill, and the effect of various drill geometries were discussed in analytical fashion.
395 citations
TL;DR: In this article, the effects of backup plate on delamination in composite materials using saw drill and core drill were analyzed and compared with that without backup plate, showing that the use of back-up plate does reduce the delamination.
Abstract: Machining of composites has caught greater attention in manufacturing of structural parts in aerospace, automobile and sporting goods Composite materials have advantageous features in strength and stiffness coupled with lightweight compared to the conventional metallic materials Amongst all machining operations, drilling is the most commonly applied method for generating holes for riveting and fastening the structural assembly Delamination is one of the serious concerns in drilling holes in composite materials at the bottom surface of the workpiece (drill exit) Quite a few references of the drilling of fiber-reinforced plastics report that the quality of cut is strongly dependent on drilling parameter as well as the drill geometry Saw drills and core drills produce less delamination than twist drills by distributing the drilling thrust toward the hole periphery Delamination can be effectively reduced or eliminated by slowing down the feed rate when approaching the exit and by using back-up plates to support and counteract the deflection of the composite laminate leading to exit side delaminations The use of the back-up does reduce the delamination in practice, which its effects have not been well explained in analytical fashion This paper predicts the effects of backup plate on delamination in drilling composite materials using saw drill and core drill The critical drilling thrust force at the onset of delamination is calculated and compared with that without backup The well known advantage of industrial use of backup can be understood fundamentally by the fact that the threshold thrust force at the onset of delamination is increased making the delamination less induced
185 citations
TL;DR: In this article, the thrust force of a step-core drill with various parameters (diameter ratio, feed rate, and spindle speed) was investigated for carbon fiber reinforced plastics (CFRP) laminates.
155 citations
TL;DR: In this article, a new compound core-special drill was developed to solve the problems of relative motion and chip removal between the outer and inner drill in drilling CFRP composite laminates.
Abstract: Drilling is the mostly used secondary machining of the fiber reinforced composite laminates, while the delamination occurs frequently at the drill exit in the workpiece. In the industrial experiences, core drill shows better drilling quality than twist drill. However, chip removal is a troublesome problem when using the core drill. Conventional compound core-special drills (core-special drills and step-core-special drills) are designed to avoid the chip removal clog in drilling. But the cutting velocity ratio (relative motion) between outer drill and inner drill is null for conventional compound core-special drills. The current study develops a new device and to solve the problems of relative motion and chip removal between the outer and inner drills in drilling CFRP composite laminates. In addition, this study investigates the influence of drilling parameters (cutting velocity ratio, feed rate, stretch, inner drill type and inner drill diameter) on thrust force of compound core-special drills. An innovative device can be consulted in application of compound core-special drill in different industries in the future.
132 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 9 |
| 2020 | 21 |
| 2019 | 27 |
| 2018 | 29 |
| 2017 | 42 |
| 2016 | 49 |