Browse Topic: Fastening
ABSTRACT In this paper a new bolt attachment method was explored, where the attaching bolts were divided into two sets. The first set of bolts was tightened and was used to connect the underbody plate to the hull under ordinary operations. The second set of bolts connecting the plate and the hull were not tightened and had some extra axial freedom. Under blast loading, the first set of bolts would break due to high tensile and shear loads, but the second set of bolts would survive due to extra axial freedom which allows the plate and the hull vibrate and separate from each other to a certain extent. A simulation model was developed to verify this concept. Three underbody plate-hull connection approaches were simulated and analyzed: 1) all tightened bolts, 2) some bolts not fully seated, 3) all bolts not fully seated. The simulation results show that with option 1), 100% of the bolts broke under the blast loading. With option 2) the not fully seated bolts survived and continued to
Heavy vehicles such as construction machinery generally require a large traction force. For this reason, axle components are equipped with a final reduction gear to provide a structure that can generate a large traction force. Basic analysis of vertical load, horizontal load (traction force), centrifugal force, and torsional torque applied to the wheels of heavy vehicles such as construction machinery and industrial vehicles, as well as actual working load analysis during actual operations, were conducted and compiled into a load analysis diagram. The loosening tendency of wheel bolts and nuts that fasten the wheel under actual working load was measured, and the loosening analysis method was presented. The causes of wheel fall-off accidents in heavy trucks, which have recently become a problem, were examined. Wheel bolts are generally tightened by the calibrated wrench method using a torque wrench. The method is susceptible to variations in friction coefficient and tightening torque
The Electroimpact Automatic Fan Cowl Riveter exhibits new and unique design features and automated process capabilities that address and overcome three primary technical challenges. The first challenge is satisfying the customer-driven requirement to access the entire fastening area of the fan cowl doors. This necessitates a unique machine design which is capable of fitting ‘inside’ a fan cowl door radius. The second challenge is determining drill geometry and drill process parameters which can produce consistent and high-quality countersunk holes in varying mixed-metal stack-up combinations consisting of aluminum, titanium, and stainless steel. The third challenge is providing the capability of fully automatic wet installation of hollow-ended titanium rivets. This requires an IML-side countersinking operation, depositing sealant throughout the OML and IML countersinks and the hole, automatically feeding and inserting a rivet which is only 5mm long and 6mm in head diameter and flaring
This SAE Recommended Practice includes wheel mounting elements subject to standardization in a series of industrial and agricultural disc wheels. The disc may be reversible or nonreversible and concave or convex. (See Figure 1 and Table 1
Efforts toward the mechanization of aircraft manufacturing began as a divided focus between devices like power tools that augment human worker capability and purpose-designed, “monument” automation. While both have benefits and limitations, the capability of modern industrial robots has grown to the point of being able to effectively fill the capability gap between them, offering a third option in the mechanization toolbox. Moreover, increasing computer processing power continues to enable more advanced approaches to perception to inform task planning and execution. Higher performance robots supplemented with greater ability to adapt to various conditions and scenarios have also led to the ability to operate reliably and safely outside traditional fixed-installation, caged work cells. This in turn has made it feasible for robot systems to work in ever more complex environments and applications, including the world of aircraft assembly with its numerous challenges like workpiece scale
As the aerospace industry moves toward determinate assembly and ever-tighter manufacturing tolerances, there is a need for automated, high-precision milling, trimming and drilling equipment that is specialized for aerospace applications. Precision countersinking is a common requirement for aircraft parts, but this is not a process that typical general-purpose milling machines are able to accommodate without the use of specialty tools such as depth-stop tool holders. To meet this need, Electroimpact has designed a 5-axis milling machine with high-speed clamping capability for countersink depth control. A custom trunnion and head with a quill and an additional clamp axis provide clamping functionality similar in speed and precision to a riveting machine, while maintaining the accuracy and features of a conventional machining center. An additional focus on design for pre-compensation accuracy has allowed the system to achieve post-compensation path and positioning tolerances that are
Spring clips (inner and outer) and associated PTFE single split cushion designed to support metric metal tubes (or inch tubes, using the inch series cushion
The torque required to tighten any threaded joint is different from the necessary torque to untighten threaded bolt or nut, and it is not observed or widely known since this is a regular and straightforward operation. Typically the torque needed to untighten a newly tightened clamp is around 10% to 30% less than the torque to stretch it further. During tightening a threaded bolt, a significant amount of torque required to overcome friction in the threads and under the nut face. The proportion of the torque used to overcome frictional resistance depends upon the friction value. When we tighten a joint with a coefficient of friction of 0.12, only about approximately 14% of the torque required to stretch the fastener producing the clamp load with 86% of the torque is lost overcoming friction. The torque needed to pull the bolt always acts in the untightening direction, resulted in untightening torque lags behind the tightening torque. Sufficient preload has to be there in the bolted joint
This paper presents a method of using CAE to determine the pre-load and torque applied to a U-Bolt rear Spring Seat. In this paper it is review two U-bolt design and the stresses generated by the pre-load torque applied, based in this study a process to determine the minimal preload and the torque is discussed. By this process it is possible to determine the minimum Torque and the correct pre-load in the U-Bolt element and assuring the correct fastening of the components avoiding over stress in the Bar elements
Gluing is an essential fastening step in the field of aircraft assembly except for riveting and bolting. Generally, the robotic programs of gluing are generated in CAM environment. Due to the positioning errors and deformation of the workpiece to be glued in the fixture, the nominal pose and the actual pose of the workpiece are no longer consistent with each other. The Robot trajectory of dispensing glue is adjusted manually according to the actual pose of the workpiece by robot teaching. In this paper, an on-line gluing path correction method is developed by 2D laser profile measurement. A pose calibration method for 2D laser profiler integrated into a gluing robot by measuring a fixed center point of a standard ball is proposed to identify the position and orientation of the laser sensor, which enables the accurate transforming coordinates between the robot frame and the sensor frame. Since there are corner points in the cross-section between two workpieces to be glued together, an
Human-machine interaction (HMI) technologies enable the automation of various manufacturing and assembly applications while maintaining high flexibility. In this context, human-robot collaboration (HRC) capable robots should no longer function as autonomous systems, but much more as assistance systems or as colleagues for workers. In connection with shorter product life cycles, increasing variant diversity and individualization, the challenge arises to set up flexible robot systems, which can be reprogrammed and commissioned with little effort in a short period of time with preservation of the required accuracies [1]. Therefore, intelligent path planning is essential for development of flexible robot systems. In this paper the development of different approaches are presented that allow the worker on the shop floor to rapidly and easily program a robot to implement new motion tasks based on a camera and sensor system without programming knowledge. Thereby various points are selected
The static coefficient of friction between lining and shoe plays a fundamental role in the lining fixing project, which is the most important parameter for the riveted joint calculation. For the lining riveting, the rivet needs to ensure that friction material and shoe remain in contact through the normal force applied on the surfaces, but the rivet should not be exposed to shear forces. Thus, the brake torque transmission must occur through the static coefficient of friction between lining and shoe, not allowing relative slips or movements between the pair in contact. Therefore, the present study aims to understand the influence of the static friction coefficient between lining and shoe as a function of the lining internal superficial roughness, from the evaluation of different roughness conditions - contact area with shoe -. The static coefficient of friction between lining and shoe is a complex measurement to be performed, due to the cylindrical geometry of the drum brake system, so
This SAE Recommended Practice provides a uniform procedure and performance requirements for evaluating fastening systems for normal highway use on aftermarket passenger cars and light trucks (except dual wheels, which are covered by SAE J1965) and multipurpose passenger vehicles. The fastening system includes the wheel, wheel bolts, and wheel nuts, as well as vehicle mating surface. The coefficients of friction for steel and aluminum mating surfaces are provided based on information available. Many factors must be considered in design and validation of wheel attachments for each specific vehicle. Where the procedure is used for original equipment applications the vehicle manufacturers specifications supersede those noted
The lower control arm (LCA) is a part of the front suspension system which is mounted on chassis with flexible rubber bushing through-bolted joint which allows the control arm to swing up and down, absorb road bumps and reduce noise and vibrations as front wheels roll over bump or potholes. In bolted joints, torque is applied so as the joint develops a certain preload that is higher than the external loads and losses acting on the joint. But the loss of preload is evident over time which causes quality problems, reworks, or even joint failures. While moving over speed breakers/obstacles abnormal squeak noise is observed in the vehicle due to torque loss in the LCA joint. The intent of this study is to determine preload requirements in LCA joint and various factors contributing to preload loss by performing joint integrity analysis in CAE. Road load data acquisition (RLDA) with Wheel Force Transducer (WFT) is performed for different testing tracks. Loads on the LCA joint are simulated
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