Hot Idea for Camshaft Assembly
Looking for ways to decrease weight in the vicinity of the powertrain? Consider making an assembled, or composite, camshaft instead of one machined and ground from solid. To be sure, assembling the cam(s) and the shaft is not a new thing, but there are some potential problems associated with the way that the process is ordinarily done. Relying on press-fitting, knurling, and/or spline/serrated gearing can lead to situations where the components being assembled are deformed. Clearly not an advantage.
Machine builder EMAG (emag.com) has developed an alternative process for the camshaft assembly, which uses thermal joining, or heat shrinking the cam onto the tube. By heating the cam, then using a robot to place the part on the shaft, high precision location can be achieved. Fusion gaps of <15 µm can be achieved. It is possible that finish grinding isn’t necessary. In the event that grinding is required, then EMAG has a VTC DS series that can be used in coordination with the heat shrink system; the robot can simply remove the part from one machine and place it in the other.
The heat shrinking process allows a variety of materials to be used, such as forged or sintered cams. Cam geometries such as negative radii can be readily achieved with the process.
The system also facilitates throughput by allowing one cam to be preheated while another is being shrunk onto a shaft.
The VA 700 T machine, for example, can handle a workpiece up to 41 in. long, with a maximum part diameter of 4 in. The individual parts to be joined can weigh up to 1.1 lb., with the total assembly up to 44 lb.
Accurate View for Assembly
Dealing with the complexity in assembly operations can be simplified through the use of the SHAPEMATCH3D sensor developed by ISRA Vision (isravision.com). The complexity the sensor addresses includes things like locating holes, edges, radii, and even randomly formed surfaces on material including metal, glass and plastic—and doing the location while the part is in motion, on the assembly line. The color of the material being measured doesn’t have an effect on the results, nor does ambient light.
What the SHAPEMATCH3D sensor does is combine multi-line projection with 3D form matching and LED illumination. The redundancy of using multiple lines means that more highly accurate results can be obtained; the sensor achieves an accuracy of 0.01 mm for each dimension, so sensor-based assembly operations can be performed with a high level of confidence.
The sensors can be used in stationary or mobile applications (e.g., with a robot). The sensors are pre-wired and temperature compensated.
There is a graphical user interface used, based on Windows XP. According to ISRA Vision, which has an array of vision-based systems, no expertise in vision is necessary for system setup (they’ve taken care of that part of things).
Medical to Auto
Although the MH3BM robot from Motoman Robotics (motoman.com) was developed for use in the medical industry—the “BM” in its name stands for “BioMedical”—the company notes that there is applicability in other industries for assembly applications, where cleanliness is critical, which includes an increasing number of jobs within auto.
The robot has a 31.7-in. reach, and a 6.6-lb payload capacity. The base, which rotates 360°, measures just 7.9 in. Utilities are routed through the bottom of the robot. There are brakes on all axes. The MH3BM can be floor-, wall- or ceiling-mounted. Thanks to built-in collision avoidance, multiple robots can be used in concert.
Renault-Nissan’s “Big Module Approach”
The Renault-Nissan Alliance is focusing on assembly modularization and simplification in order to drive down entry costs per model by 30 to 40% as well as reduce part costs by 20 to 30%.
They’re calling this initiative CMF—Common Module Family. The first Nissan vehicles to be based on CMF will appear in late 2013: replacements for the Rogue, Qashqai, and X-Trail. The first Renault vehicles will appear in late 2014: replacements for the Espace, Scénic, and Laguna.
CMF is based on what they call “Big Modules.” These modules include the engine bay, cockpit, front underbody, rear underbody, and electrical/electronic architecture.
The approach is to standardize within the modules, then to increase the number of vehicles that can be built based on given platforms. According to the Alliance: “CMF is not a platform; it can involve several platforms. A platform is a horizontal segmentation; a CMF is a cross-sector concept.”
By creating the Big Modules, they’re able to share and carryover parts from one model to another, thereby increasing economies of scale.
According to Jean-Michel Billig, Engineering, Quality & IT director at Renault, “With CMF, the investments in vehicle architecture and non-visual parts are mutualized, resulting in significant cost reductions that allow us to roll out our innovation policy in terms of environment, safety and new technologies for all our customers.”
And the creation of what they’re calling an “Alliance parts bank” of the components forming the Big Modules undoubtedly reduce assembly tooling costs, as well.