Rod-hole deformation is overcome by providing a two- or, optionally, three-piece design. It is therefore an object of the present invention to provide an end bearing structure comprising a race with an integrated spacer, and a hammer blade with an integrated bearing surface. An additional object is to provide an optional third piece comprising a separate liner installed between the bearing and race surfaces in order to mitigate elongation of the hammer blade pivot hole immediately adjacent to the pivot rod, the liner can also serve as a coating to reduce the friction and wear between the race and the blade to increase service life in elevated dynamic loading situations. A further object is to improve the ease and safety of installation and maintenance of hammer blades within a hammer mill. Still another object is to eliminate unnecessary spacers between the hammer blades when installed onto the pivot rods.
Effecting the above objects results in a stronger bearing structure designed to deflect and lessen the dynamic side loading on the hammer blade when in motion and under load. Reduction in wear on the leading, bottom, and trailing edges of the hammer by infusing an unyielding material ultimately increase the life cycle of the hammer blade and reduces costs associated with replacement and maintenance of the hammer mill.
In a hammer mill, including a housing defining a hammer mill grinding chamber with at least one inlet and one outlet, a rotor is disposed centrally in the housing for rotation about a rotor axis of rotation. A screen is disposed at a predetermined radial location relative to the rotor's axis of rotation. Operatively, pivotally attached to the rotor is a plurality of hammers grouped in sets and disposed periodically about the rotor's axis of rotation. All hammers within a single set have a common axis of rotation lying parallel to the rotor's axis of rotation. The hammers' axes of rotation are disposed at a common radial distance relative to the rotor's axis of rotation. At least one of the hammers in each group has an opening in one end corresponding to the common hammer axis of rotation.
The present invention may be manufactured using methods of forging, casting or rolling, as are well known by those having skill in the art.
The hammers require no new installation procedures or equipment. The present invention eliminates the need to utilize spacers. This is accomplished through a variable length race with an integrated spacer. The width of the race with the integrated spacer may range from one quarter to ten inches. This design feature reduces installation time and improves the overall safety to the personnel assembling or maintaining the hammer mill due to the lessening of the need to align hammers, spacers and rods during installation. The installation is also safer for users as with a typical setup, rods must be forced through holes using impact devices while the operator manually holds the spacers. Utilizing the incorporated spacers the operators' hands are clear from pinch points within the mill.
Established forging techniques, well known in the art of fitting two-piece bearing like structures together, are used in the manufacture of the two-piece end bearing structure disclosed herein.
The inner race, with the integrated spacer, augments the two-piece end bearing structure by maintaining a predetermined distance between one or more hammer blades when installed on the pivot rod within the hammer mill. The inner race also improves the two-piece end bearing structure by assisting in the dispersal of anticipated dynamic forces that ultimately affect the hammer blade assembly and the hammer mill pivot rod. This additional feature reduces fatigue, and stress and enhances resistance to deformation and inordinate wear acquired through use. The life of the hammer blade assembly is, therefore, extended.
Installation of hammers with races integrated with the spacer is also made easier and quicker, whether the installation is initial or replacement. It is also predicted to improve the safety of this procedure in the field by reducing the number of parts and alignment issues associated with existing hammer blades and hammer mills