FIELD OF INVENTION

[0001] The present invention relates to the mechanical field. More specifically, the present invention is related to an improved sawmill used for sawing objects. BACKGROUND

[0002] Sawmills are used principally in woodworking, metalworking, and lumbering. FIG. 1 is a schematic of a sawmill (100) as known in the prior art. Conventionally, AC Induction motors are used in sawmills. AC induction motors are heavy and large and bulky so special arrangements are required for mounting AC induction motors. We cannot directly drive band wheel from an AC induction motor. These motors require two additional pulleys, an additional shaft, extra supporting bearing blocks, and a belt for coupling and speed reduction and also an extra belt tensioning mechanism for motor.

[0003] In ordinary sawmill design heavy induction motor, extra pulleys; coupling components and motor fittings make one side very much heavier compared to free wheel side. So counter weights are required to balance weight. This makes system complicated, heavy, bulky, space consuming and expensive.

[0004] Due to this, heavy lifting mechanism and supporting assemblies are required to lift band saw assembly while working. Further, as the number of parts increases, it becomes more complicated to make alignment between belt and pulleys. [0005] Moreover, starting torque of induction motors are less compared to the torque when an Induction motor is running because of the use of starter and due to some other factors. Due to these reason frequent starting and stopping is troublesome. If power is cut off while cutting a log the saw blade will get jammed inside the log. More torque is required to drive saw blade from this position. Due to the fact that starting torque of induction motors are less compared to the torque when an Induction motor is running. It will be difficult for an induction motor to pull saw blade from the j ammed position. Induction motors with more power rating is used to overcome this problem in ordinary sawmills thus results in wasting more energy.

[0006] Therefore, despite of the advancement offered by prior art, a need remains for further improvements. In view of aforementioned, it is required to provide an improved system and method of data security that can overcome the limitations and disadvantages of the prior arts. SUMMARY OF THE INVENTION

[0007] Embodiments of the present invention disclose an improved sawmill. The improved sawmill includes a BLDC hub motor, band wheel, band blade, motor and worm gear box, freewheel, vertical carriage lifting mechanism, and a mounting support for BLDC hub motor. The BLDC hub motor is adapted to drive a band blade driving wheel. The band wheel is directly mounted on BLDC hub motor. [0008] It is an object of the present invention to provide an improved sawmill which eliminates the need of induction motor and additional parts of balancing the weight as used in conventional sawmills.

[0009] It is another object of the present invention to provide present invention to provide an improved sawmill which consist of Brushless DC motor and other control systems for enable Brushless DC motor to operate saw band directly.

[0010] It is a further object of the present invention to provide an improved sawmill which is compact and capable of operating with batteries during power cut.

[0011] It is a further object of the present invention to provide an improved sawmill which is portable and easily transportable.

[0012] It is yet an object of the present invention to provide an improved sawmill which is capable of saving 70% run time energy as compared with conventional Induction motor sawmills.

[0013] It is yet an object of the present invention to provide an improved sawmill which is having higher throughput and durability of motor as the brushless dc motor enabled to be off during the return stroke after finishing a cutting stroke and during set works to save run-time energy.

[0014] This invention is pointed out particularly with the appended claims. Additional features and the advantages of the present invention will become apparent to those skilled in the art by referring to the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWING

[0015] Other objects, features, and advantages of the present subject matter will be apparent from the following description when read with reference to the accompanying drawings. Drawings are illustrated with different views according to different embodiments of the invention:

[0016] FIG. l is a schematic of a sawmill device as known in the prior art.

[0017] FIG. 2 is a schematic of an improved sawmill (10) in accordance with an embodiment of the present invention.

[0018] FIG. 3 is a schematic of an improved sawmill (10) in accordance with another embodiment of the present invention.

[0019] FIG. 4 is a schematic of an improved sawmill (10) in accordance with another embodiment of the present invention.

[0020] FIG. 5 is a schematic of an improved sawmill (10) in accordance with another embodiment of the present invention.

[0021] FIG. 6 is a schematic of an improved sawmill (10) in accordance with another embodiment of the present invention.

[0022] The various elements of the present invention as illustrated in figures are:

1 : (Brushless DC) BLDC hub motor;

2: Band wheel;

3: Band blade;

4: Motor and worm gear box;

5: Freewheel;

6: Vertical carriage lifting mechanism, and 7 : BLDC hub motor mounting support.

DETAILED DESCRIPTION OF EMBODIMENTS

[0023] The present invention will now be described in brief with reference to the accompanying drawings. Now, refer in more detail to the exemplary drawings for the purposes of illustrating non-limiting embodiments of the present invention.

[0024] An embodiment of present invention provides an improved sawmill (10). Referring to FIG. 1, the improved sawmill (10) includes a BLDC hub motor (1), Band wheel (2), Band blade (3), Motor and worm gear box (4), Freewheel (5), Vertical carriage lifting mechanism (6) and a mounting support (7) for BLDC hub motor.

[0025] In an embodiment of the present invention, a BLDC hub motor (1) is adapted to drive a band blade driving wheel. The Band wheel (2) is directly mounted on BLDC hub motor (1).

[0026] In an embodiment of the present invention further the motor and worm gear box (4) for the vertical movement of vertical carriage on which BLDC hub motor, band wheels, band blade are mounted.

[0027] In an embodiment of the present invention, FIG. 3 depicts the back view of the improved sawmill (10). FIG. 4 depicts the right side view of the improved sawmill (10). FIG. 5 depicts the top view of the improved sawmill (10). In an embodiment of the present invention, the BLDC hub motor (1) is dust proof, water proof (with ip65 specification). Further, in the improved sawmill (10), there are no other protruding parts which results in a compact design. Due to removal of induction motor and additional parts, the weight and size of sawmill is also considerably reduced.

[0028] As shown in FIG. 6, the improved sawmill (10) enables the use of BLDC hub motor (1) in band sawmill to directly drive band wheel (2) which further drives the drive band blade (3).

[0029] In an embodiment of present invention, to make an advanced sawmill with features such as energy efficient, less resource hungry, less complicated, weight reduced, more controllable, ergonomic, more safe to work etc. the conventional method of using AC Induction motors to drive band saw blade in sawmill machine is replaced with a more convenient BLDC hub motor (1) which directly drive band saw wheel (2) in saw mill.

[0030] In some embodiments, for installment of BLDC hub motor (1) to drive band saw wheel directly various modifications have been made, and also significant design changes its electrical systems, electronics and control systems are made. These changes have resulted lot of advantages to the sawmill (10).

[0031] The major advantage of the present invention is that with the BLDC hub motor (1), sawmill (10) became very much simplified. No other protruding parts and a compact design results by the use of BLDC hub motor in design. The weight and size of sawmill also considerably reduced. Further, the reduction in number of parts, the servicing, handling and transportation of the machine is also simplified. Secondly, the other machine elements such as lifting motor, lifting gear, chain etc. are also became small and less power consuming. Considering further advantages, with present invention, greasing and other types of lubrication and pollution caused by lubricating materials are reduced due to reduced number of moving parts.

[0032] In an embodiment of the present invention, there is no need of mechanical motor starter like star delta starter for the BLDC hub motor (1) as in conventional sawmills with high power AC induction. Further, with present invention, the frequent starting and stopping of BLDC hub motor (1) is possible. Therefore, it is feasible to switch off BLDC hub motor (1) of present invention during the return stroke i.e. when machine returning to its start position after finishing a cutting stroke and also during set works. This way the present invention is efficiently save more than 40% of energy as motor is not working for 50% time. Further, the improved sawmill with BLDC hub motor (1) can run at higher power rating than its rated power for a short interval of time. Thus, additional energy saving is resulted.

[0033] In a further embodiment of the present invention, the improved sawmill (10) is designed to run in a low power mode by control electronics when less energy is required like when cutting logs with small diameter. This also saves energy. Further, due to reduced parts, the energy consumed by pulleys, connecting shaft, friction in these parts and belt slippage is saved. Thus, with these features approximately 70% energy is saved which is one of the main advantages of this design.

[0034] Also, due to less run time of motor, motor life is also elongated. Further, the band saw blade (3) and band wheels (2) are running for lesser time. So wear and tear are reduced which results in improved blade life and increasing duration between band wheel reconditioning. [0035] The present invention is also efficient in saving space and cost due to reduction in components. The BLDC hub motor (1) used in the present invention is light weight as compared to induction motor for same power rating. Further, extra pulleys, coupling components and motor fittings are not required. So weight unbalance problem is almost eliminated and counter weight is not required which saves space and material.

[0036] The BLDC motors are electronically controlled by a BLDC motor driver, therefore precise control of motor is possible. The speed of BLDC motors are independent of AC mains power supply where as in AC induction motor speed varies with the fluctuations in mains supply frequency which produce vibrations in band blade cause marks in the cut wood, thus reducing quality of cut wood. These problems are eliminated in the present invention. The BLDC hub motor (1) works at lesser DC voltage typically less than lOOv DC which will not cause harm to human life while AC induction motor used in normal sawmill works at 3 phase 415 V AC which is dangerous to human life in case of any negligence by the operator.

[0037] In a band saw machine, most of the sound is produced when band blade is running due to metal to metal contact between band blade and band wheel. In present invention, the band blade is driven by the motor only less than half of working time of sawmill machine. So sound pollution is reduced to half.

[0038] In an embodiment of the present invention, the improved sawmill (l0)is adapted to run on battery which makes the improved sawmill (10) working during power cuts. This further eliminates the need of generator and hence reduces cost, expense of fuel in generator, and also eliminates air pollution and sound pollution produced by the generator.

[0039] In an embodiment of the present invention, the improved sawmill (10) with BLDC hub motor (1) as drive motor is portable in nature. For portability, battery and transporting wheels are added. This sawmill machine is more environment friendly and light weight to transport when compared to ordinary gasoline or diesel engine powered portable sawmills.

[0040] In addition to the above mentioned examples, various other modifications and alterations of the invention may be made without departing from the invention. Accordingly, the above disclosure is not to be considered as limiting and the appended claims are to be interpreted as encompassing the true spirit and the entire scope of the invention. As it will be readily apparent to those skilled in the art, the present invention may easily be produced in other specific forms without departing from its essential characteristics. The present embodiment is, therefore, to be considered as merely illustrative and not restrictive.