Pellet mill

Abstract

 The invention describes an extrusion mill with a mill frame, a stationary installed extrusion roller frame in subject mill frame, with at least a single extrusion roller and a drum shaped die surrounding the roller frame, which rotates relatively to the roller frame by driving means. The driving means exist out of a stationary component of the extrusion mill which is executed as the stator of an electrical motor and a die, which is executed as the rotor of an electrical motor. It is also possible that the die is stationary relatively to the mill frame and the roller frame rotates relatively to the die. Here a stationary component of the extrusion mill is executed as the stator of an electrical motor and the roller frame executed as the rotor of an electrical motor.

Description

[0001] The invention relates primarily to an extrusion mill with a frame, a stationary extrusion roller frame installed within the frame, supporting at least a single extrusion roller with a drum shaped die installed around the extrusion rollers, which is rotated relatively to the extrusion roller frame by means of a driving mechanism.

[0002] A known extrusion mill concept features an extrusion roller frame which is generally stationary within the extrusion mill frame. The extrusion rollers rotate around generally stationary extrusion roller shafts which are supported by the extrusion roller frame. To produce pellets, the extrusion rollers cooperate with a drum shaped die installed around the extrusion rollers. The drum shaped die is rotated by means of a driving mechanism.

[0003] At known extrusion mill concept, a gear or pulley is installed at the circumference of the drum shaped die, which engages with a pinion shaft or belts, installed in the extrusion mill frame which is driven by a motor. To obtain a stable support of the rotating die, at which significant operating loads need to be absorbed, the die is generally supported by bearings, installed around the generally stationary extrusion roller frame or in the ,partly surrounding, stationary extrusion mill frame. Seals are applied between various relatively to each other, moving parts of the extrusion mill.

[0004] This known extrusion mill concept features a number of disadvantages. Adequate sealing is required to prevent oil and grease leakage. In spite of this sealing, contamination of palletized products by lubricants can often not be prevented. Besides that, machine components required to drive these known extrusion mill concepts require regular maintenance, which results in a productivity reduction of subject extrusion mill concepts. These drive components feature an energy transmission loss, which reduce the energy efficiency of the extrusion mill.

[0005] The invention foresees in an extrusion mill of described type at which these disadvantages in a simple, though effective manner, are eliminated.

[0006] The extrusion mill according the invention features the characteristic of a driving mechanism which integrates the stationary housing of an electrical motor with the stationary extrusion mill frame and rotary shaft of the electrical motor with the rotary die support.
The described construction according the invention leads to a number of important advantages. The electrical motor stator and rotor interact in principle without friction, which obsolete the need of lubrication. Complicated lubricant seals are no longer required. A minimum wear takes place which limit maintenance efforts to an absolute minimum. The extrusion mill according described invention does not suffer from transmission losses because a transmission as applied at known extrusion mill concept is not applied. Because of this, an extrusion mill according the invention can increase performance at identical energy consumption.

[0007] The stationary extrusion mill frame can be integrated with a stationary motor component. However, the generally stationary extrusion roller carrier can be integrated with the stationary motor component as well.

[0008] In the previous description of the extrusion mill , the extrusion roller frame is considered to be generally stationary relatively to the extrusion mill frame, while the die is rotating around the extrusion roller frame , relatively to the extrusion mill frame. Evidently, it is possible to give the die a stationary position and have the extrusion roller frame (together with the supported extrusion rollers) rotating relatively to the die and extrusion mill support frame. Because of this, an alternative construction of the extrusion mill is mentioned with a stationary mill frame, a rotary extrusion roller frame which supports at least a single extrusion roller with a stationary drum shape die, surrounding the extrusion roller, were the roller frame rotates relatively to the die by driving means which integrates the stationary and rotary component of an electrical motor and extrusion mill.

[0009] This alternative construction of the extrusion mill according the invention is based on the same inventive idea and therefore the same advantages can be obtained as described by the first construction.

[0010] In this case, the die can be executed as stator, yet the possibility exists to execute the extrusion mill frame as stator.

[0011] Besides the previously mentioned advantages, typical characteristic of the extrusion mill according the invention is a construction with a limited number, simple components, which makes it possible to keep the manufacturing cost of the extrusion mill according the invention low.

[0012] The invention is described below by means of a single diagram where a cross section of a construction alternative for the extrusion mill according the invention is displayed .

[0013] In the diagram, only the components required to understand the invention are displayed, while an outline of other components is displayed because a knowledgeable individual will understand the actual execution of the construction .

[0014] The partly drawn extrusion mill in the diagram is equipped with a mill frame 1 and an installed, stationary extrusion roller frame 2. The stationary roller frame is shaped like a tube by means of any known process to allow installation of not displayed lines, required for controlling the extrusion roller 3 at the front end of the roller support frame 2. The extrusion rollers rotate around the roller shafts 4.

[0015] The extrusion roller frame 2 is surrounded by the drum shaped die 5 at the position of the extrusion roller 3. The drum shaped die extension 6 is supported by support points in the mill frame 1. Bearings 7 are sketched in the diagram between die extension 6 and mill frame 1. Besides that, bearings 8 are placed between inner circumference die extension 6 and outer circumference extrusion roller frame 2 for a stable die support. An axial bearing 9 and seal 10 are part of the construction.

[0016] At the outer circumference of die extension 6, an electrical coil 11 is mounted which makes the die extension 6 function as the rotor in an electrical motor. In a similar way, electrical coil 12 is installed at the inner side of the mill frame 1, which makes the mill frame function as the stator in an electrical motor. The combination of mill frame 1 and die extension 6 with die 5 forms in principle an electrical motor at which die extension 6 with die 5 functions as the electrical motor shaft. In this fashion, die 5 can be directly driven in a simple way.

[0017] At displayed construction with stationary extrusion roller frame 2, it is possible to install electrical coil 12 at the outer circumference of extrusion roller frame 2, at which the electrical coil 11 at the inner circumference of die extension 6 is installed.

[0018] Evidently, the possibility exists to install die extension 6 with die 5 stationary in the mill frame 1 by which roller frame 2 in mill frame 1 can rotate relatively to die 5. In subject situation, the electrical coil 11 is installed at the outer circumference of roller frame 2 and electrical coil 12 at the inner side of die extension 6 (or mill frame 1). In this way, the extrusion roller frame 2 functions as rotor and die extension 6 (or mill frame 1) as stator of an electrical motor. The principle of the invention does not change because of this.

[0019] The invention is not limited to described alternative constructions which can be changed in a number of ways with in the limitations of the claims. Besides, it is possible that both die and extrusion roller frame can rotate relatively to a stationary mill frame.

Claims

1. Extrusion mill with mill frame, a stationary extrusion roller frame, installed in subject mill frame, featuring at least a single extrusion roll with a drum shaped die surrounding the extrusion roll, which rotates relatively to the extrusion roller frame by driving means, with the characteristic, that the driving means exist out of a stationary part of the extrusion mill and die, were the stationary extrusion mill component is executed as stator and the die is executed as rotor from an electrical motor.

2. Extrusion mill according claim 1, with the characteristic, that the mill frame is executed as stator.

3. Extrusion mill according conclusion 1, with the characteristic, that the extrusion roller frame is executed as stator.

4. Extrusion mill with mill frame, an installed extrusion roller frame which can rotate in the mill frame, with at least a single extrusion roller, surrounded by a drum shaped die, at which the roller frame rotates relatively to the die by driving means, with the characteristic, that the driving means exist out of a stationary component of the extrusion mill which is executed as the stator of an electrical motor and roller frame, which is executed as the rotor of an electrical motor.

5. Extrusion mill according claim 4, with the characteristic, that the die is executed as stator.

6. Extrusion mill according claim 4, with the characteristic, that the extrusion mill frame is executed as stator.

Drawing