Elliptical acetabuliform blade for shredder

The present invention relates to an elliptical acetabuliform blade for shredder, where a sheet metal is punched by a mold to integrally form an elliptical acetabuliform blade, where the periphery of elliptical blade is integrally formed into serration. The serrated periphery extending horizontally inwards to integrally form a planar disk for cutting paper along a longitudinal direction serves as a flank. The two ends along the major axis of the elliptical flank are each integrally formed into a hooked edge for cutting the paper along a longitudinal direction to form paper chips having double-tapering ends. These characteristics help to reduce the manufacturing cost, reduce the motor load and power consumption, to thereby enhance the market competitiveness.

FIELD OF THE INVENTION

The present invention relates to an improved cutting blade for a shredder, especially to an elliptical acetabuliform blade that is integrally formed by punching a sheet metal in a mold machine.

BACKGROUND OF THE INVENTION

The conventional shredders for cutting paper use a plurality of cutting blades and spacers engaging over a rotary cutter shaft, and the shearing force that two parallel and opposite rotary cutter shafts produce for transferring and cutting the paper-to-be-cut along a longitudinal direction into strips. Shredders can be classed into two types, the stripe-cut shredders and crosscut shredders, according to the machine cutting style. The former shredders arrange cutting blades to the rotating cutter shafts in a manner to cutting the paper in a longitudinal direction to form strips. The later shredders include blades that include more than one cutting edge, and each cutter is disposed helically along the rotary cutter shaft for first cutting paper along a longitudinal direction into strips and then cutting paper along a horizontal direction into approximate 4 mm×40 mm paper chips.

By referring to the assembled perspective view of a conventional blade illustrated inFIG. 1and a planar view showing the operation of the conventional blade inFIG. 2, the conventional blade is made by punching a sheet metal having a thickness of approximately 2 mm into a circular blade by a mold. The blade includes a polygonal central hole A1through which a rotary shaft may pass. The blade also includes cutting edges A2that are spaced in 120 degrees apart around the periphery. As shown, when two blades are arranged on the rotary shafts B in a back-to-back manner to combine into a set of blades A, the cutting edges of the two blades assume a V-like edge A3. The opposite rotary shafts B′ space the two blades apart by spacer (not shown) in a face-to-face manner to form a set of blade A′. When the paper-to-be-cut passes through the two reverse rotary shafts B, B′, the opposing rotation of the periphery of the blades, that is, flanks A4and flanks A4, will cut the paper like scissors. The opposing rotation of cutting edges A2and the opposite flanks A4will then cut the paper along a horizontal direction into 4 mm×40 mm paper chips.

During operating of the conventional blades, to ensure smooth cutting of the paper along the horizontal direction, sharp blades with proper orientations are needed. However, because the blades are formed by a punch molding, the mold wear that increases with the time will reduce sharpness of the blade edges, which does not improve until replacing the mold, to result in inconsistent quality. To ensure quality of the blades, it is necessary to shorten the service term of the mold, which results in increment of the cost. In addition, in the conventional blades, the thickness of the blade is the same as the width of the paper-to-be-cut. To ensure the strength of blades while cutting along the horizontal direction, the blades cannot be too thin, or else the blades tend to deform or fracture. Such a limitation attributes to the high material cost, which is less competitive as compared to the current market price. In addition, because the thickness of the conventional blades is same as the width of the paper-to-be-cut, and because the location of the width define the horizontal cutting points, the narrower width of cross-section is, the smaller output power is needed to cut along the horizontal direction. In other words, the motor can supply a minimum power for cutting along the horizontal direction, that is, to reduce the power consumed by the motor. But because of the width of the paper-to-be-cut by the conventional blades is 4 mm, the motor needs to output higher power to drive the blades and flanks moving in opposing directions to cut the paper along the horizontal direction smoothly.

SUMMARY OF THE INVENTION

In view of the above, this invention overcomes the shortcoming of the conventional blades.

The main objective of the present invention is to provide an elliptical acetebuliform blade for shredders, that is integrally punched from a sheet metal in a mold into an elliptical acetabuliform blade to effectively reduce the material cost and the weigh of the blade to thereby reduce the motor loading and power consumption.

Another objective of the present invention is to provide an elliptical acetabuliform blade for shredders, that uses the change in the curvature of the elliptical acetabuliform blade to cut paper into paper chips each having a wider center and tapering towards the ends, so as to reduce the power that that motor needs to output for cutting the two ends to thereby reduce the motor loading and the power consumption.

To realize the above objectives, in the present invention, a sheet metal is punched by a mold to integrally form an elliptical acetabuliform blade, where the periphery of elliptical blade is integrally formed into serration. The serrated periphery extending horizontally inwards to integrally form a planar disk for cutting paper along a longitudinal direction serves as a flank. The two ends along the major axis of the elliptical of the flank are integrally formed into a hooked edge for cutting the paper along a longitudinal direction to form paper chips having double-tapering ends. An inner edge of the flank then integrally extends inwards and downwards to form an arc base and then a circular base. A polygonal hole is formed in a center of the circular base, through which a rotary shaft may pass.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be described in further detail hereinafter, with reference to accompanying drawings.

Please refer toFIGS. 3 to 5, whereFIG. 3illustrates the planar view of the present invention, andFIGS. 4 and 5are cross-sectional views taken from lines4—4and line5—5inFIG. 3, respectively. The above-mentioned views disclose a revolutionized cutting blade1for a shredder, which blade is able to provide an optimum sheet capacity based on the various types of shredders. The present invention selects a sheet metal having a thickness of 0.2 mm as a raw material, the selected sheet metal is punched into an elliptical acetabuliform blade by a mold. The periphery11(shown in the enlarged view ofFIG. 3) of the elliptical blade is integrally formed into serration110. The periphery11of serration serves to pull the paper-to-be-cut downwards. The acetabuliform periphery11extending horizontally inwards to integrally form a planar disk for cutting paper along a longitudinal direction serves as a flank12. The two ends along the major axis of the elliptical flank12are each integrally formed into a hooked edge13for cutting the paper along a longitudinal direction to form paper chips having double-tapering ends. An inner edge120of the flank12integrally extends inwards and downwards to form an arc base14and then a circular base15. A polygonal hole16is formed in a center of the circular base15, through which a rotary shaft may pass.

As shown in the assembled perspective view of the present invention inFIG. 6, the standardized elliptical acetabuliform blades punched from a sheet metal by a mold are arranged sequentially on two rotary shafts to be assembled into the rotary cutting tool that is most important for a shredder. During assembly, the elliptical acetabuliform blades on one of the rotary shafts are arranged by alternating in forward and reversed orientations. The elliptical acetabuliform blades on the other rotary shaft are then arranged by alternating in reversed and forwards orientations.

As exemplified inFIG. 6, the first blade21and the second blade22on a lower first rotary shaft2are arranged by alternating in the forward and reversed orientations. Because the blades extend from an inner periphery of flank inwards and downwards to form an arc base and then a circular base, the circular base of the first blade21and second blade22join to contact each other while the hooked edges of the first blade21and the second blade22are separated from each other to assume an open space23. On the other hand, the first blade31and second blade32on an upper second rotary shaft3are arranged by alternating in the forward and inversed orientations. Similarly, because the blades extend from the inner periphery of the flanks inwards and downwards to form an arc base and then a circular base, the circular base of the first blade31and second blade32are separated from each other, while the hooked edges of the first blade31and the second blade322are joined to contact each other. By adopting such arrangement, when the two rotary shafts rotate in opposing directions, the hooked edges33of the first blade31and the second blade32on the upper second rotary shaft3after contacting each other adapt to insert into the open space23of the first blade21and second blade22on the lower first rotary shaft2.

As shown in the operating views inFIGS. 7 and 8, the standardized elliptical acetabuliform blades enable the flanks of the corresponding blade set to maintain a certain contact gap at all time by means of the changes between the major axis and minor axis of the elliptical blades and the curvatures of the blades. In other words, while viewing from the rear projection, the superposition of the blades arranged on different rotary shafts are constant. Such a constant superposition can ensure scissors like cutting effects between the flanks12when the two rotary shafts rotate in opposing directions (shown inFIG. 7). When the cutting edges13of the corresponding opposite blades on the two ends of elliptical major axis rotate to the elliptical major axis, the hooked edges13on the major axis of the elliptical blades will cooperate with the flanks12on the minor axis of the mating elliptical blades to cut off the paper strips (as shown inFIG. 8).

FIGS. 9 and 10illustrate the schematic views of the elliptical acetabuliform blade of the present invention fragmenting paper after cutting, and the paper after being cut by the elliptical acetabuliform blade of the present invention. Along with the changing of the curvatures of the elliptical acetabuliform blades, the paper is fragmented into paper chips4each having a wider center42and tapering towards the ends41. Because of the two ends41of the paper chip4are the horizontal cutting positions, the narrower width of cross-section is, the smaller output power is needed to cut along the horizontal direction. In other words, the motor can supply a minimum power for cutting along the horizontal direction under a minimum load. The reduction in the motor load also reduces the power consumption and increases service-life of the motor.

In addition, the conventional blade is punched from a sheet metal having thickness of about 2 mm, while the elliptical acetabuliform blade of the present invention may be punched from a sheet metal having a minimum thickness of 0.2 mm, where the costs of the two materials are significantly different, and the reduced weight also helps to further reduce the power that the motor needs to supply to thereby increase the service-life of the motor and reduce the power consumption. These characteristics help to reduce the manufacturing cost and enhance the market competitiveness.

In summary, according to the present invention, a sheet metal may be punched into elliptical acetabuliform blades, where the periphery of each elliptical blade is integrally made into serration. The serrated periphery extending horizontally inwards to integrally form a planar disk for cutting paper along a longitudinal direction serves as a flank. The two ends along the major axis of the elliptical flank are each integrally formed into a hooked edge for cutting the paper along a longitudinal direction to form paper chips having double-tapering ends. The revolutionized construction of the present invention reduces power consumption, material cost, and lessens motor load, so as to enhance the market competitiveness of the shredder.

In the present specification “comprises means “includes or consists of” and “comprising” means “including or consisting of”.