Slow speed hammermill for size reduction of wood chips

A hammermill having a housing with an inlet for receiving wood, bark and oversized wood chips and a rotor assembly disposed within the housing for reducing the size of the wood, bark and oversized chips to wood chips having a desired size comprising:

• a screen bar assembly having a plurality of screen bars spaced from each other and secured within the housing adjacent to the rotor assembly;
• the rotor assembly having a generally cylindrical configuration with a longitudinal axis of rotation extending through the housing;
• the rotor assembly disposed between the inlet of the housing and the screen bar assembly;
• the screen bar assembly having a generally semicircular configuration with a radius of curvature compatible with the configuration of the rotor assembly;
• the screen bars extending substantially parallel with the longitudinal axis of the rotor assembly;
• a plurality of flexible hammers pivotally attached to the rotor assembly to allow limited movement of each flexible hammer radially inward and outward relative to the rotor assembly;
• a beveled surface formed on one edge of each screen bar adjacent to the rotor assembly whereby the flexible hammers cooperate with the beveled edges of the screen bars to form the wood chips having the desired size;
• and
• each flexible hammer including a hook head having at least one tearing edge formed on a respective crushing element to impact the wood, bark and oversized wood chips.

A hammermill for reducing oversized wood chips comprising:

• a housing having an inlet to receive the oversized wood chips;
• a rotor assembly disposed in the housing having a plurality of flexible hammers pivotally secured therewith to contact the oversized wood chips introduced through the inlet;
• the rotor assembly having a generally cylindrical configuration with a longitudinal axis corresponding to the axis of rotation of the rotor assembly;
• each flexible hammer having a radially extended position which generally describes a circle as the rotor assembly revolves;
• a screen bar assembly disposed below the rotor assembly adjacent to the circle;
• the screen bar assembly having a plurality of screen bars radially spaced from each other and secured within the housing;
• a pair of bearing assemblies mounted on and secured to the housing
• the rotor assembly including a shaft extending through the housing and rotatably mounted on the bearing assemblies;
• a plurality of rotor disks concentrically disposed on and secured to the shaft;
• a plurality of support bars extending longitudinally through the rotor disks adjacent to the outside diameter of the rotor disk;
• the flexible hammers cooperating with the support bars to allow limited radial movement of each flexible hammer between its radially extended position and a radially retracted position relative to the shaft of the rotor assembly as the flexible hammers contact oversized wood chips;
• each screen bar having a longitudinal edge disposed adjacent to the rotor assembly;
• and
• a beveled surface formed on the longitudinal edge of each screen bar adjacent to the rotor assembly.

A hammermill for reducing oversized wood chips comprising:

• a housing having an inlet to receive the oversized wood chips;
• a rotor assembly disposed in the housing having a plurality of flexible hammers pivotally secured therewith to contact the oversized wood chips introduced through the inlet;
• the rotor assembly having a generally cylindrical configuration with a longitudinal axis corresponding to the axis of rotation of the rotor assembly;
• each flexible hammer having a radially extended position which generally describes a circle as the rotor assembly revolves;
• a screen bar assembly disposed below the rotor assembly adjacent to the circle;
• the screen bar assembly having a plurality of screen bars radially spaced from each other and secured within the housing;
• a pair of bearing assemblies mounted on and secured to the housing
• the rotor assembly including a shaft extending through the housing and rotatably mounted on the bearing assemblies;
• a plurality of rotor disks concentrically disposed on and secured to the shaft;
• a plurality of support bars extending longitudinally through the rotor disks adjacent to the outside diameter of the rotor disk;
• the flexible hammers cooperating with the support bars to allow limited radial movement of each flexible hammer between its radially extended position and a radially retracted position relative to the shaft of the rotor assembly as the flexible hammers contact oversized wood chips;
• each flexible hammer including a hammer body having a moment arm with a first opening formed at one end of the moment arm;
• the first opening having dimensions selected to allow inserting a first support rod therethrough;
• a crushing element formed on the hammer body opposite from the first opening;
• a second opening having a generally elongated configuration formed in the hammer body intermediate the first opening and the crushing element;
• the moment arm extending generally from the first opening through the second opening to an exterior portion of the crushing element;
• and
• a second support rod disposed within the second opening to allow only limited movement of the respective flexible hammer radially inward and radially outward during rotation of the rotor assembly.