Duplicating grinding machine

Abstract

Abstract This invention relates to a duplicating grinding machine for grinding workpieces of irregular three-dimensional shape, wherein a model and at least one workpiece are mounted side by side in spaced parallel relation to one another between clamping devices so as to be synchronously rotatable about their longitudinal axes, said model and each of said workpieces having associated therewith two carrier arms each, one carrier arm associated with said model and at least one carrier arm associated with said workpiece being interconnected to form a unit and adapted to be brought into pressing engagement with said model and said associated workpiece, respectively, with one carrier arm of a first interconnected unit carrying a scanning roller for scanning said model and adapted to be translated along the length of said model and each other carrier arm of said first unit carrying a motor-driven belt grinding assembly having an endless grinding belt looped around a return roller and a contact roller, and with one carrier arm of a second interconnected unit carrying a second scanning roller for scanning said model opposite said first scanning roller, and each other carrier arm of said second unit carrying a second motor-driven belt grinding assembly disposed opposite said first belt grinding assembly and having a grinding belt provided with a different grinding layer and also looped around a return roller and a contact roller. BACKGROUND OF THE INVENTION A duplicating grinding machine of the above described type is known from DT-OS No. 2,311,011. In this machine there is provided a model adapted to be scanned by two scanning rollers. Each of the two scanning rollers is connected to a separate belt grinding assembly through an individual carrier arm unit. For rational working of the workpiece, one belt grinding assembly is provided with a coarse grinding belt, and the other, with a fine grinding belt. This arrangement permits the workpiece to be shaped to its final form in a single cycle of operations from a wooden block without any preshaping, or to be coarse- and fine-ground subsequent to preshaping. In various technical fields, use is made of shaped objects not consisting of a homogenous material, such as wood, but comprising two or more materials. Shaping of such objects is conventionally performed in such a manner that individual parts thereof are separately shaped to matching forms and are then assembled, or that the individual parts are separately preshaped to a certain degree of accuracy, whereupon they are assembled and finished manually, such as by hand-grinding. The reason for this separate shaping or preshaping resides in the fact that different materials require different working technologies. It is generally known that the milling tools required for milling metals are different from those required for milling plastics or wood. The same applies to grinding or different materials. Depending on hardness and other properties of such materials, the grinding material employed is required to have different properties with respect to grain size, grain embedding, material of grains, elasticity of the grinding belt etc.. Employ of the wrong type of grinding belt for a specific material may result in rapid wear of the grinding belt. Thus a wood grinding belt employed for grinding metal will be blunted very rapidly. Workpieces consisting of several materials are encountered rather often in practice, examples being rifle stocks, golf club heads etc. These workpieces frequently comprise a material combination of wood and metal, or wood and plastics, respectively. A golf club head usually comprises all three of these materials. Accordingly, there has for considerable time existed a demand, for instance in the weapons industry, for a solution permitting a more rational working of workpieces consisting of different materials. It is therefore an object of the invention to provide an improved duplicating grinding machine of the type described above, permitting to finish workpieces consisting of different materials in a single cycle of operations and preferably on all sides. In order to attain this object, the invention provides that for grinding on all sides and in a single cycle of operations a workpiece consisting of at least two materials having different grinding properties, such as of wood and metal, the model is divided into at least two partial models complementing one another with respect to accurate working of the workpiece on all sides in such a manner that at least one working shape surface for engaging the belt grinding assembly with the workpiece under the control of the scanning roll of one partial model is offset with respect to at least one such working shape surface of the other partial model, and that in the remaining shaping region each partial model comprises raised portions, wherein one partial model for grinding one of said materials is associated with the scanning roller of the first carrier arm unit, which is provided with a belt grinding assembly suitable for working the first material, while the other partial model for grinding the second material is associated with the scanning roller of the second carrier arm unit, itself provided with a belt grinding assembly suitable for working said second material. In the duplicating grinding machine according to the invention there are as many partial models as there are materials having different grinding properties in the workpiece. In such cases, in which a plastics material is employed having the same grinding properties as wood, it is not required to provide a separate partial model for working said plastics material. The partial models have a configuration resulting in the operative engagement of the associated belt grinding assembly being positively restricted to that portion of the workpiece for the working of which the respective belt grinding assembly is provided. In those portions not to be worked by a particular belt grinding assembly, the scanning roller guides the belt grinding assembly past the workpiece. The duplicating grinding machine according to the invention offers the great advantage that it is now possible to finish a ready-assembled workpiece consisting of different materials without any hand-finishing, a feat which was hitherto not possible. This results in a considerable rationalization and corresponding economies in the production. Further the duplicating grinding machine according to the invention permits to achieve a very high degree of accuracy in shaping a workpiece in a very simple manner. In an advantageous embodiment the invention provides that the partial models are located side by side in a single plane and that the two carrier arm units are disposed opposite one another with respect to the partial models. If two carrier arm units are employed, this constitutes the most efficient arrangement, since the carrier arm units may then be translatably mounted laterally of the clamping devices for the workpieces and models without interfering with one another. Certain workpieces may require overlapping working by two or more belt grinding assemblies. This may specifically be the case in interface areas where a smooth transition is required. In this case it is advantageous if the working shape surfaces of the partial model controlling working of the harder material are disposed in overlapping relation with the working shape surfaces of the other partial model. In this manner it is ensured that only the belt grinding assembly provided for working the harder material grinds over the softer material. This does not result in the harder grinding belt being damaged, although the finish achieved on the softer material will then not be as smooth as that achieved with the grinding belt provided for this particular material. In another advantageous embodiment the invention provides that the grinding belt employed for the harder material is longer than the other one. This results in the durability of the two belts being substantially equal, since the wear per length unit of the grinding belt provided for the harder material will then be reduced due to its increased length.

Inventors

• 👤 Erich Schmidt

Bibliographic Details