Machine tools are built based on cast-iron bodies. Cast iron well dumps down vibrations and is dimensionally stable. Therefore, many conventional machine tools are modernized and modified into CNC machine tools based on the seasoned old bodies of those machine tools. Nevertheless, CNC machine tools are also manufactured based on polymer concrete, which vibration damping ability is even better. On the other hand, attempts made in the past by leading machine tool manufacturers to use welded frames in CNC machine tools failed. The revival of interest in welded frames was spurred by economic considerations, as steel systems are much thinner compared to cast-iron ones. They are able to carry the same loads. The construction of CNC machine tools with a welded steel frame undertaken at the Institute of Mechanical Technologies (ITM) of the Czestochowa University of Technology is an attempt to solve this constructional problem. The machine tool frame was designed with use of CAD solid works system. The ultimate success of using the welded frame is determined not only by the frame itself, but also generally the design of the machine tool and its operation parameters. The welded frame was used for a high-accuracy three-axis milling machine. In this respect, it is equal of professional machine tools manufactured by reputed companies. It can be either a production machine tool or a test stand.

The article has presented a numerical method for determining the gear ratio function and the gearing line of the toothed gear. The described algorithm, explained on the example of planar gearing, can be used also for the analysis of spatial gearings. Assembly errors have been allowed for in the gear model.

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Classic methods of machining cylindrical gears, such as hobbing or circumferential chiseling, require the use of expensive special machine tools and dedicated tools, which makes production unprofitable, especially in small and medium series. Today, special attention is paid to the technology of making gears using universal CNC (computer numerical control) machine tools with standard cheap tools. On the basis of the presented mathematical model, a software was developed to generate a code that controls a machine tool for machining cylindrical gears with straight and modified tooth line using the multipass method. Made of steel 16MnCr5, gear wheels with a straight tooth line and with a longitudinally modified convex-convex tooth line were machined on a five-axis CNC milling machine DMG MORI CMX50U, using solid carbide milling cutters (cylindrical and ball end) for processing. The manufactured gears were inspected on a ZEISS coordinate measuring machine, using the software Gear Pro Involute. The conformity of the outline, the tooth line, and the gear pitch were assessed. The side surfaces of the teeth after machining according to the planned strategy were also assessed; the tests were carried out using the optical microscope Alicona Infinite Focus G5 and the contact profilographometer Taylor Hobson, Talysurf 120. The presented method is able to provide a very good quality of machined gears in relation to competing methods. The great advantage of this method is the use of a tool that is not geometrically related to the shape of the machined gear profile, which allows the production of cylindrical gears with a tooth and profile line other than the standard.

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Spur gears have a wide application in the machine-building industry. Machining process primarily selected for these gears is hobbing method with modular hobs, or with Fellows cutters. Other methods which can be applied are profiling using the pull broaches, while the finishing can be done by gear shaving or grinding by the Maag, Niles or Reishauer methods. Moreover, in small (or unit) production, they may be formed using disc-or finger-type modular cutters. The article presents a method for cutting spur gears using a disc-type mill with a variable cutting plate profile. The influence of the number of blades of the presented milling cutter on the accuracy of the worked tooth profile was investigated.

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