A ROUTER BIT WITH REPLACEABLE BLADE INSERTS

Abstract: A cutting tool with replaceable blade inserts comprises a body (1) having distal and proximal sides, the body having a shank (2) projecting from the body proximate side, the shank designed to be rotated around a rotatory axis, wherein the body has two substantially parallel grooves (16) on the body distal side, wherein two blade inserts (6, 7) are provided, each with a cutting edge (22, 10) and an opposing blunt edge (20, 21), one of the two blade inserts is inserted into one of the two substantially parallel grooves.

Description: A ROUTER BIT WITH REPLACEABLE BLADE INSERTS FIELD OF INVENTION The present invention relates to woodworking. More particularly it relates to a router bit for woodworking with replaceable blade inserts. BACKGROUND OF THE INVENTION Routers are widely used tools for woodworking in furniture manufacture. A router bit is a rotatable cutting tool for woodworking, which has a blade or several blades attached to it, that is guided, automatically or manually, while rotating at a high speed, through the wood being processed, cutting, cutting or chopping it, to produce a groove or an edge of a predetermined profile on the wood. Router bits in general comprise three main parts: the shank, the body and the blades. The shank is an elongated shaft, projecting from the body of the tool, that is installed in an automated machine that facilitates rotary motion of the tool. The tool's body has grooves that allow splinter disposal. The blades may be characterized by the way the blades are attached to the body. One type of router bits is characterized by the blades being brazed to the router bit's body, and the other type of router bits has replaceable blade inserts. An example of a brazed blade cutting tool is disclosed in UK Patent Application No. 8702671 , filed Feb. 6, 1987, published as GB 2186220A. An example of a router bit with replaceable blades is disclosed in our IL Patent application No. 122044, filed Oct. 28, 1997. The cutting tool that has brazed blades renders the tool extra strength due to the fact that the blades are tightly attached to the cutting tool, and its cost is lower than the replaceable blades cutting tool. Nevertheless, if a blade breaks or is damaged, the whole cutting tool needs to be replaced. Another disadvantage of the cutting tool with brazed blades, in comparison with the replaceable blades cutting tool, is that in the brazing process, the inner structure of the blade (usually made of tungsten carbide) may be damaged by exposure to the high temperatures involved. Replaceable blade inserts which are attached by screws, on the other hand, ensure the cutting tool's prolonged use because of their better durability, and lower maintenance costs, since in the case of a blade insert being broken, only the blade insert needs replacement. However, the tool's overall cost is higher than the brazed blade cutting tool. The replacement of blade inserts in the replaceable blade insert cutting tools is usually relatively simple and safe. One of the major hazards involved in using cutting tools is the possible kickback of the cutting tool, caused by violent deep uncontrolled entry of the blade into the wood being processed, that kicks back the cutting tool unexpectedly, and may result in injury of the user or damage to the cutting tool or the wood being processed. This can happen in cases where the cutting tool is held in a bad position relative to the wood, like a sharp angle, or in the case of replaceable blade inserts cutting tool, when the blade inserts are not inserted correctly. In order to prevent kickback of the cutting tool, the cutting tool is provided with body that is designed to act as a safety means. In brazed blade cutting tools, the body is shaped to correspond to the profile of the blade, and the blade is brazed with its cutting edge only slightly protruding from the body. This way the body itself prevents the cutting tool from entering the processed wood too deep, and thus prevents the cutting tool from being kickbacked. Cutting tool blades are usually made of some kind of a hard metal, such as tungsten carbide. The quality of the woodworking depends considerably on the sharpness of the cutting edge of the blade. BRIEF DESCRIPTION OF THE INVENTION It is the object of the present invention to provide a cutting tool with replaceable blade inserts for woodworking that is versatile, and yet durable and safe to use. It is another object of the present invention to provide a cutting tool for woodworking with replaceable blade inserts whose body need not be shaped to correspond to a particular blade profile, and therefore allow the use of blades with a variety of profiles. It is thus provided a cutting tool with replaceable blade inserts, in accordance with a preferred embodiment of the present invention, said tool comprising a body having distal and proximal sides. The body has a shank projecting from the body proximal side, designed to be rotated around a rotatory axis. The body has two substantially parallel grooves on said body distal side, and two blade inserts are provided, each having a cutting edge and an opposing blunt edge. One of said two blade inserts is inserted into one of said two substantially parallel grooves, and the other one of said two blade inserts is inserted into the other one of said two substantially parallel grooves, so that the cutting edge and the opposing blunt edge of each one of said two blade inserts protrude from said body perpendicularly to said rotatory axis. The cutting edge of each one of said two blade inserts faces the blunt edge of the other one of said two blade inserts, and the cutting edge of each one of said two blade inserts further protrudes relative to the blunt edge of the other one of said two blade inserts. Furthermore, in accordance with another preferred embodiment of the present invention, said body is cylindrically shaped. Furthermore, in accordance with another preferred embodiment of the present invention, said body is provided with two opposite concavities. Furthermore, in accordance with another preferred embodiment of the present invention, said body has 180° symmetry around said rotatory axis. Furthermore, in accordance with another preferred embodiment of the present invention, said tool is installed in an automated machine that provides rotatory motion to the cutting tool, along its symmetry axis. Furthermore, in accordance with another preferred embodiment of the present invention, a broad notch is carved inside the cutting tool's body, in order to accommodate the blade inserts. Furthermore, in accordance with another preferred embodiment of the present invention, said broad notch is carved from one said concavity to the other. Furthermore, in accordance with another preferred embodiment of the present invention, broad notch is provided with two substantially parallel deeper grooves, along the bottom of said broad notch in two opposing sides, into which the blade inserts are inserted. Furthermore, in accordance with another preferred embodiment of the present invention, a wedge is positioned between said blade inserts. Furthermore, in accordance with another preferred embodiment of the present invention, a passage is drilled along the body, perpendicular to said grooves, and opens into said grooves. Furthermore, in accordance with another preferred embodiment of the present invention, a passage is drilled along the body's diameter and perpendicular to said grooves, and opens into said grooves. Furthermore, in accordance with another preferred embodiment of the present invention, said passage is cylindrical. Furthermore, in accordance with another preferred embodiment of the present invention, through said passage, a metal pin is threaded, fully inserted. Furthermore, in accordance with another preferred embodiment of the present invention, near each one of the external openings of said passage, an additional bore is provided, drilled parallelly to said passage and passing up to the proximal side-wall of said broad notch. Furthermore, in accordance with another preferred embodiment of the present invention, said bore is provided with internal threading. Furthermore, in accordance with another preferred embodiment of the present invention, said two blade inserts are made of hard metal. Furthermore, in accordance with another preferred embodiment of the present invention, said blade inserts are made of tungsten carbide. Furthermore, in accordance with another preferred embodiment of the present invention, said two blade inserts has similar profiles that can be selected from a variety of profiles. Furthermore, in accordance with another preferred embodiment of the present invention, each blade insert is provided with a recess designed to accommodate said pin portion exposed in the groove. Furthermore, in accordance with another preferred embodiment of the present invention, each blade insert is provided with a bore, and a screw is screwed through said bore in said body, and through said bore in said blade insert and fastened against the wedge. Furthermore, in accordance with another preferred embodiment of the present invention, said cutting tool's body is metallic. Furthermore, in accordance with another preferred embodiment of the present invention, said blade inserts are replaced when said cutting edge becomes blunt. It is thus provided another cutting tool with replaceable blade inserts, in accordance with yet another preferred embodiment of the present invention, said cutting tool comprising a body having distal and proximal sides, said body having a shank projecting from said body proximal side, said shank designed to be rotated around a rotatory axis, said body having a rod projecting from said body distal side along said rotatory axis, wherein said body has two substantially parallel grooves on said body distal side, wherein two blade inserts are inserted into said grooves, each one of said blade inserts is inserted into a groove, so that the cutting edge and the opposing blunt edge of each one of said two blade inserts protrude from said body, wherein the cutting edge of one of said two blade inserts faces the blunt edge of the other of said two blade inserts, and wherein the cutting edge of each one of said two blade inserts further protrudes from the blunt edge of the other of said two blade inserts, wherein each one of said two blade inserts is further held in position by means of a restrainer mounted on said rod. Furthermore, in accordance with another preferred embodiment of the present invention, said body is a plate that resembles a rectangle with chopped corners, with two opposing concavities on its short sides. Furthermore, in accordance with another preferred embodiment of the present invention, said body is metallic. Furthermore, in accordance with another preferred embodiment of the present invention, said rotatory axis preferably passing through the body's center of mass. Furthermore, in accordance with another preferred embodiment of the present invention, said shank is a shaft designated to be installed in an automated machine that provides rotatory motion to said cutting tool. Furthermore, in accordance with another preferred embodiment of the present invention, an external threading is provided on the distal end of said rod. Furthermore, in accordance with another preferred embodiment of the present invention, said two substantially parallel grooves are substantially parallel to the longer sides of said rectangular plate. Furthermore, in accordance with another preferred embodiment of the present invention, two bores are drilled through said plate, parallel to said shank, and open into said grooves. Furthermore, in accordance with another preferred embodiment of the present invention, said two bores are provided with internal threading to allow a screw to be screwed in. Furthermore, in accordance with another preferred embodiment of the present invention, said screw is Elen-type screw. Furthermore, in accordance with another preferred embodiment of the present invention, said two blade inserts are made of a hard metal. Furthermore, in accordance with another preferred embodiment of the present invention, said two blade inserts are made of tungsten carbide. Furthermore, in accordance with another preferred embodiment of the present invention, said two blade inserts has similar profiles that can be selected from a variety of profiles. Furthermore, in accordance with another preferred embodiment of the present invention, each blade insert is provided with a recess, said recess is designed to accommodate the project portion of said screw. Furthermore, in accordance with another preferred embodiment of the present invention, said restrainer is in the form of an annular ring with two substantially parallel grooves, said parallel grooves directed at said cutting tool's body. Furthermore, in accordance with another preferred embodiment of the present invention, said blade inserts are each provided with a recess that is predesigned to fit into said grooves on said restrainer. Furthermore, in accordance with another preferred embodiment of the present invention, said restrainer circumscribes the distal side of said rod. Furthermore, in accordance with another preferred embodiment of the present invention, the cleft between said grooves on said restrainer is smaller than the cleft between said grooves on the body, so that said blade inserts are tilted with respect to said body and incline towards said rod. Furthermore, in accordance with another preferred embodiment of the present invention, attached to the restrainer, is a ball-bearing circumscribing said rod, and mounted from said rod distal end. Furthermore, in accordance with another preferred embodiment of the present invention, the outer diameter of said ball-bearing is larger than said restrainer diameter. Furthermore, in accordance with another preferred embodiment of the present invention, a nut is screwed on the distal end of said rod. Furthermore, in accordance with another preferred embodiment of the present invention, a nut is screwed on the distal end of said rod. Furthermore, in accordance with another preferred embodiment of the present invention, blade inserts are replaced when said cutting edge become blunt. Furthermore, in accordance to another preferred embodiment of the present invention, said restrainer is provided with two projecting walls, wherein the inner surface of each wall is tilted in a predetermined angle so that said inner surface is substantially parallel and adjacent to each of said blade's plane. Finally, in accordance to another preferred embodiment of the present invention, each of said projecting walls is provided with two protrusions that fit into corresponding recesses provided on said body. BRIEF DESCRIPTION OF THE FIGURES Figure 1. illustrates a general view of a cutting tool with replaceable blade inserts, in accordance with a preferred embodiment of the present invention, in its assembled state with two replaceable blade inserts. Figure 2. illustrates an exploded view of the parts that comprise a cutting tool with replaceable blade inserts, in accordance with a preferred embodiment of the present invention, shown in Figure 1. Figure 3. illustrates three views of the assembled cutting tool of the present invention shown in Figure 2. A. a frontal view, B. a side view and C. a view from the shank's side. Figure 4. shows the relative position of two blade inserts, when aligned on a cutting tool in accordance with a preferred embodiment of the present invention. Figure 5. illustrates a general view of a cutting tool with replaceable blade inserts, in accordance with yet another preferred embodiment of the present invention, in its assembled state with two replaceable blade inserts and a ball-bearing. Figure 6. illustrates an exploded view of the parts that comprise a cutting tool with replaceable blade inserts, in accordance with yet another preferred embodiment of the present invention, shown in Figure 5. Figure 7. illustrates three views of the assembled cutting tool of the present invention shown in Figure 6. A. a frontal view, B. a side view and C. a view from the ball-bearing side. Figure 8. shows the relative position of two blade inserts, on a cutting tool in accordance with yet another preferred embodiment of the present invention. Figure 9 illustrates a general view of a cutting tool with replaceable blade inserts, in accordance with yet another preferred embodiment of the present invention, in its assembled state with two replaceable blade inserts, a ball-bearing and a safety blades lock. Figure 10. illustrates an exploded view of the parts that comprise a cutting tool with replaceable blade inserts, in accordance with yet another preferred embodiment of the present invention, shown in Figure 9. Figure 11. illustrates three views of the assembled cutting tool of the present invention shown in Figure 9. A. a frontal view, B. a side view and C. a view from the shank's side. Figure 12 illustrates three views of a restrainer provided with safety means to be incorporated with a cutting tool of the present invention shown in Figure 9. A. a frontal view, B. a side view and C. a view from the side conjugated the tool's body. DETAILED DESCRIPTION OF THE PRESENT INVENTION AND FIGURES The present invention provides a novel design of a cutting tool having replaceable blade inserts, suitable for industry, workshops, craftsmen and do- it-yourself carpenters. This is mainly due to the simplicity of the blade insert loading and consequent versatility of use. It is thus provided a cutting tool with replaceable blade inserts, in accordance with a preferred embodiment of the present invention, the cutting tool with replaceable blade inserts comprising a body having distal and proximal sides. The body has a shank projecting from the body proximal side, designed to be rotated around a rotatory axis. The body has two substantially parallel grooves on said body distal side, and two blade insert are provided, each having a cutting edge and an opposing blunt edge. One of said two blade inserts is inserted into one of said two substantially parallel grooves, and the other one of said two blade inserts is inserted into the other one of said two substantially parallel grooves, so that the cutting edge and the opposing blunt edge of each one of said two blade inserts protrude from said body perpendicularly to said rotatory axis. The cutting edge of each one of said two blade inserts faces the blunt edge of the other one of said two blade inserts, and the cutting edge of each one of said two blade inserts further protrudes relative to the blunt edge of the other one of said two blade inserts. Reference is now made to Figure 1 , illustrating a general view of a cutting tool with replaceable blade inserts, in accordance with a preferred embodiment of the present invention, in its assembled state with two replaceable blade inserts. The cutting tool's body (designated by numeral 1) is cylindrically shaped, provided with two opposite concavities (24) on the side wall of the body. A body having at least 180° symmetry around the rotatory axis is preferable since this fact minimizes the risk of vibrations during rotation. A cylindrically shaped body is even more preferable since it is symmetrical at any angle around the rotatory axis. The body is preferably made of metal, and is preferably produced in turning, gnawing, sharpening and coating processes. The body (1), which possesses rotatory symmetry, has distal and proximal sides. The body (1) has a shank (2) projecting from the center of the body's proximal side along the symmetry axis of the body. This shank acts as the shaft designated to be installed in an automated machine (not shown in the figures) that provides rotatory motion to the cutting tool, along its symmetry axis. On the body's distal side, a broad notch (3, better appreciated in Fig. 2) is carved inside the cutting tool's body (1), in order to accommodate the blade inserts. The notch (3) is provided with two substantially parallel deeper grooves (16, better seen in Fig. 3B), along the bottom of the notch in two opposing sides, into which the blade inserts are inserted. These two grooves are provided in order to allow support for the blade inserts prior to the final fastening of the device. A wedge (14) is positioned between the blade inserts in order to separate them and provide support. Thus, in effect, the blade inserts are positioned in two relatively deep grooves that provide the blade inserts the support needed. The notch (3) is carved from one concavity (24) to the other (24). Inside the body (1), and perpendicular to the grooves (16), a cylindrical passage (4) is drilled along the body's diameter, from one side to the other, that opens into the grooves. Through this passage (4), a metal pin (11) is threaded, fully inserted to avoid protrusion of the pin out of the body (1). Near each one of the external openings of the passage (4) an additional bore (5) is provided, drilled parallelly to the passage and passing up to the proximal side- wall of the notch (3). The bore (5) is provided with internal threading to allow a screw (12) to be screwed in. The screw is preferably an Elen-type screw to allow its full insertion inside the bore, and to avoid any protrusion out of the bore. The wedge (14), in fact, comprises two identical wedges (14A, 14B, showing in Fig 2.), adjacently positioned, each provided with a recess (80) to accommodate the distal tip of the screw (12), in order to prevent jerking of the wedge, as a result of centrifugal force exerted on it by the rotational movement of the tool. Two blade inserts (6, 7) made of a hard metal, preferably tungsten carbide are inserted into the notch (3), and positioned inside the grooves (16). One of the blade inserts is inserted into one groove, and the other blade insert is inserted into the other groove. The cutting edge and the opposing blunt edge of each one of the blade inserts protrude from the body perpendicularly to the rotatory axis. The cutting edge of each one of the blade inserts faces the blunt edge of the other blade insert. It is possible to use blade inserts with cutting edges having different profiles, depending on the required performance, provided that both blade inserts have the same profile (or else the resulting profile of the groove or edge being carved by the cutting tool in the processed wood would be a superposition of the different blades' profiles). Note the different blade insert profiles presented in the figures (Fig. 1-3 present a typical blade insert with an L-shaped cutting edge profile, whereas Fig. 4 presents a blade insert with a curved cutting edge profile, Fig. 8 presents another curved profile). Each blade insert is positioned inside the groove, so that the cutting edge and the opposing blunt edge of each one of the two blade inserts protrude from the cylindrical body circumference. In order to allow better tightening of the blade inserts to the body and prevent undesired blade insert movement, each blade insert is provided with a recess (8, see Fig. 4) and a bore (9). The recess (8) is designed to accommodate the pin (11) portion exposed in the groove (16), and the bore (9) is designed to allow the screw (12) to pass through it and be fastened against the wedge. Reference is now made to Figure 4 showing the relative position of two blade inserts on a cutting tool in accordance with a preferred embodiment of the present invention. The cutting edge (22) of the proximal blade insert (6) further protrudes relative to the blunt edge (21) of the distal blade insert (7). Similarly the cutting edge (10) of the distal blade insert (7) further protrudes relative to the blunt edge (20) of the proximal blade insert (6). This alignment is in fact a main aspect of the present invention. The blunt edge of one blade insert serves as a protection that prevents the cutting edge of the other blade insert from plunging too deep into the wood being processed when the cutting tool meets the processed wood, hence preventing kickback. This feature is better understood if we consider the operation mode of the cutting tool. Reference is now made to Figure 3C illustrating a view from the shank's side of the assembled cutting tool of the present invention. The arrows (23) indicate the direction of the rotatory motion. When the cutting tool is operated (i.e. provided with rotatory motion, and introduced to the wood to be processed), the blunt edge (20) of one of the blade inserts (6) is the first to encounter the wood to be processed (81). It may scratch the wood, but does not cut into it. Immediately after, the cutting edge (10) of the consequent blade insert (7) strikes the wood. The substantially tangential encounter of the blunt edge (20) of the former blade insert enables the sharp cutting edge of the latter blade insert to strike the wood in an angle suitable for executing the chopping action. It is the blade insert with the blunt edge, and the small cleft resulting from the protrusion of the cutting edge of the blade insert relative to the blunt edge of the other blade insert, that prevents the cutting tool from plunging too deep into the processed wood. The circular broken line (82) represents the outermost operational range of the tool when rotated on the spot, and is in fact the line defined by the cuting edges of both blade inserts when the tool completes full rotation. It is important to note that the assembly of the cutting tool parts is very simple for an unprofessional worker, and there is practically no chance of positioning the blade inserts incorrectly. To be able to understand the blade insert loading procedure, reference is now made to Figure 2 that illustrates an exploded view of the parts that comprise the cutting tool with replaceable blade inserts, in accordance with a preferred embodiment of the present invention, shown in Figure 1. The body (1) of the cutting tool naked from blade inserts is shown. The two blade inserts (6, 7) are inserted in the grooves (16), each blade insert in one groove, in the same orientation as shown in this figure, while the bore (9) in each blade insert faces the bore (5) in the appropriate side of the body. The pin (11) is threaded through the passage (4) in the body and the grooves, while passing through the recess (8) in the blade inserts. This pin helps to position the blade inserts in the grooves before tightening the blade inserts. The two identical wedges (14A, 14B) forming the wedge (14), whose cross- section is trapezoid-shaped, are both placed in between the blade inserts, forcing them to press against the outer walls of the notch (3). In this state the blade inserts can be tighten. A screw (12) is screwed through the bore (5) in the body, passing through the bore (9) of the blade insert (7), and presses against the wedge, assuring a safe stationary affixing of the blade insert in the groove. Similarly the second screw (13) is screwed through the bore on the opposite side, fastening the other blade insert in place. A detailed structure of the notch (3) and the grooves (16) accommodating the blade inserts in a diagonal orientation can be seen in Figure 3B that illustrates a side view of the assembled cutting tool in accordance with a preferred embodiment of the present invention. The position of the blade inserts (6, 7) in the grooves (16) is shown, as well as the position of the wedge (14). The inclined walls of the notch and the wedge force the blade inserts to bear a diagonal orientation with respect to the body. In addition, they effectively present deeper grooves, thus provide the blade inserts the support needed. The cleft between the blade inserts allows for splinters to be conveniently disposed and cleard away. The concavities (24) are designated to allow splinters to be conveniently disposed and be removed. The assembly of this embodiment is designed to prevent any undesirable movement of the blade inserts, thus avoiding unexpected kickback or malfunctioning of the cutting tool. The cutting tool with replaceable blade inserts of the present invention can be loaded with blade inserts that have any desired profile of the cutting edge. The simplicity of blade insert loading and the possibility of reducing the dimensions of the cutting tool to a relatively small design make it appealing for industry, workshops, craftsmen and do-it-yourself carpenters. It is further provided a cutting tool with replaceable blade inserts, in accordance with another preferred embodiment of the present invention. The cutting tool comprises a body having distal and proximal sides. The body has a shank projecting from the body proximal side, said shank designed to be rotated around a rotatory axis. The body has a rod projecting from said body distal side along the rotatory axis. The body has two substantially parallel grooves on said body distal side, and two blade inserts are provided. One of said two blade inserts is inserted into one of said two substantially parallel grooves, and the other one of said two blade inserts is inserted into the other one of said two substantially parallel grooves, so that the cutting edge and the opposing blunt edge of each one of said two blade inserts protrude from said body perpendicularly to its rotatory axis. The cutting edge of each one of said two blade inserts faces the blunt edge of the other of said two blade inserts, and the cutting edge of each one of said two blade inserts further protrudes relative to the blunt edge of the other one of said two blade inserts. Each one of said two blade inserts is further held in position by means of a restrainer mounted on said rod. Reference is now made to Figure 5, illustrating a general view of a cutting tool with replaceable blade inserts, in accordance with yet another preferred embodiment of the present invention, in its assembled state with two replaceable blade inserts and a ball-bearing. The cutting tool's body (designated by numeral 30) comprises a plate (30) resembling a rectangle with chopped corners (47), with two opposing concavities (48) on the short sides. The body is preferably made of metal, and is preferably produced in turning, cutting, sharpening and coating processes. The body has distal and proximal sides. The body has a shank (31) projecting from the body's proximal side. The shank is designed to be rotated around a rotatory axis, said rotatory axis preferably passing through the body's center of mass. The shank (31) is a shaft designated to be installed in an automated machine (not shown in the figures) that provides rotatory motion to the cutting tool. The body has a rod (32) projecting from the body distal side along the rotatory axis, parallel to the shank (can not be seen in Figure 5, but better appreciated in Figure 6). An external threading (83) is provided on the distal end of the rod (32). The body's distal side is provided with two substantially parallel grooves (33, better seen in Figure 7B) and substantially parallel to the longer sides of the rectangular plate (30), into which the blade inserts are inserted. These two grooves are provided in order to allow support and alignment of the blade inserts. Two bores (34) are drilled through the plate (30), parallel to the shank, and open into the grooves. Two pins (35) are tightly pressed into the bores (34). This can be better appreciated by observing Figure 7A. One of the pins (35) protrudes into a groove (33) in a predetermined position. A second pin is similarly positioned in the second bore. Two blade inserts (36, 37) made of a hard metal, preferably tungsten carbide are inserted into the grooves (33). One of the blade inserts is inserted into one groove, and the other blade insert is inserted into the other groove. The cutting edge and the opposing blunt edge of each one of the blade inserts protrude from the body perpendicularly to the rotatory axis. The cutting edge of each one of the blade inserts faces the blunt edge of the other blade insert. It is possible to use blade inserts with cutting edges of different profiles, depending on the required performance, provided that both blade inserts have the same profile. Each blade insert is positioned inside a groove, so that the cutting edge and the opposing blunt edge of each one of the two blade inserts protrude from the body's circumference. In order to place the blade insert precisely in its final position, each blade insert is provided with a recess (38, see Fig. 8). The recess (38) is designed to accommodate the project pin (35) portion. Each one of said two blade inserts is further held in position by means of a restrainer (44) mounted on said rod (32). The restrainer, here in the form of an annular ring with two substantially parallel grooves (51) positioned on the face of the ring directed at the cutting tool's body. The blade inserts are each provided with a recess (43) that is predesigned to fit into the grooves (51) on the restrainer (44). The restrainer circumscribes the distal side of the rod (32). The purpose of the restrainer is to tighten the blade inserts in a way that will not allow any undesired movement of the blade inserts during operation in addition to the prevention of blade insert lose in case of a faulty operation or breaking of the blade insert. The distance between the grooves (51) on the restrainer (44) is smaller than the distance between the grooves (33) on the body, so that the blade inserts are tilted with respect to the body and incline towards the rod (32). This feature can be better appreciated in Figure 7B, which illustrates a side view of the assembled cutting tool of the present invention. The tilted position of the blade inserts renders the tool extra rotational stability. Another advantage gained from the tilted position of the blade inserts is fast disposal of splinters from the gnawed wood. Here too, the concavities (48) facilitate easier splinter disposal. Attached to the restrainer (44), is a ball-bearing (45) mounted over the rod (32) from its distal end. The outer diameter of the ball-bearing is preferably larger than the restrainer diameter. The ball-bearing is used to advance the cutting tool along a pattern adjacent the wood being processed, to obtain a similar pattern on the processed wood. For the purpose of fastening of the restrainer (44) and the ball-bearing (45), a nut (46) is screwed on the distal end of the rod (32). The nut secures the restrainer and the ball-bearing in place preventing undesired release of the apparatus parts. Reference is now made to Figure 8 showing the relative position of two blade inserts on a cutting tool in accordance with the same embodiment of the present invention, as illustrated in Fig. 5 (two views are provided - a view from the shank side, Fig. 8A, and a view from the blades' side, Fig. 8B). The cutting edge (39) of the proximal blade insert (36) further protrudes relative to the blunt edge (40) of the distal blade insert (37). Similarly, the cutting edge (41) of the distal blade insert (37) further protrudes relative to the blunt edge (42) of the proximal blade insert (36). As mentioned before, this alignment is in fact a main aspect of the present invention. The blunt edge of one blade insert serves as a protection that prevents the cutting edge of the other blade insert from plunging too deep into the wood being processed, hence preventing kickback. The direction of the rotation is denoted by the arrows (84). The assembly of the parts is very simple for an unprofessional worker and it is impossible to insert and position the blade inserts incorrectly. In order to understand the blade insert loading procedure, reference is made to Figure 6 that illustrates an exploded view of the parts that comprise the cutting tool with replaceable blade inserts, in accordance the same embodiment of the present invention, shown in Figure 5. The body (30) of the cutting tool naked from blade inserts is shown. The two blade inserts (36, 37) are inserted in the grooves (33), each blade insert in one groove, in the same orientation as shown in the Figure 5, while the recess (38) in each blade insert faces the bore (34) in the appropriate side of the body. The restrainer (44) is mounted over the rod (32), and rotated to a position as to allow the blade inserts (36, 37) to be inserted into the grooves (51) of the restrainer. After attaching the restrainer in a way that the recesses (43) in the blade inserts fit the grooves (51) of the restrainer (44), the ballbearing (45) is mounted over the rod. Finally, a nut (46) is screwed on the threading provided on the rod, and tightened. Final positioning and fastening is achieved by two screws (35), screwed through the bores (34, 50) in the body and protrude into the recess (38) of the blade inserts. It is evident that the blade insert loading on the cutting tool with replaceable blade inserts and a guiding ball-bearing of the present invention is simple, rendering the cutting tool versatility. This fact makes the cutting tool suitable for industry, workshops, craftsmen and do-it-yourself carpenters. Reference is now made to Figure 9, illustrating a general view of a cutting tool with replaceable blade inserts, in accordance with yet another preferred embodiment of the present invention, in its assembled state with two replaceable blade inserts, a ball-bearing and a safety blades lock. The embodiment of this cutting tool resembles the embodiment shown in Figure 5, with a restrainer having an adjustment enabling an additional safety lock of the blades. Here, the restrainer (100), which holds the two blade inserts (36 and 37) in position by two substantially parallel grooves (101), is provided with two walls (102) projecting from between the grooves and the circumference of the restrainer. Figure 12 illustrates three views of a restrainer provided with safety means to be incorporated with a cutting tool of the present invention shown in Figure 9. As can be appreciated in Figure 12A, the walls (102) of the safety means are tilted in a predetermined angle defined between the inner surface of each of the walls and the restrainer (100). This angle is determined so that the inner surface of each wall is substantially parallel to the plane of each blade and adjacent to it as can be seen in Figure 11A. The safety means serve to pevent jolting of a broken blade if a break occurs during operation. It should be noted that the cutting tool of the present invention revolves rapidly, and flying debris of a blade insert may inflict serious injury, so that the safety means are aimed at preventing hazardous dismembering of the blades. Returning to Figure 12, at the ends of the walls, each wall (102) is provided with two protrusions (103) adapted to fit into recesses (104) on the plate (30). The recesses (104) in the body can be better appreciated in Figure 11B and in the exploded view in Figure 10. In this way, the walls (102) are secured from the body's side and act as protective walls that lock the blade inserts from dismounting viloently. If a blade insert is broken or partially broken during operation, it would not eject towards the user, but rather remain stationary in position on the tool. A small niche 105 is provided on the inner surface of the walls (102) in order to accommodate the end of pins 35. This provides additional firmness and stability to the cutting tool. The assembly of the parts in this embodiment too, is very simple, and may be easily performed by an unskilled person. It is impossible to insert and position the blade inserts incorrectly. In order to understand the blade insert loading procedure, reference is made to Figure 10 that illustrates an exploded view of the parts that comprise the cutting tool with replaceable blade inserts, in accordance the same embodiment of the present invention, shown in Figure 9. It should be clear that the description of the embodiments and attached Figures set forth in this specification serves only for a better understanding of the invention, without limiting its scope as covered by the following Claims. It should also be clear that a person in the art, after reading the present specification could make adjustments or amendments to the attached Figures and above described embodiments that would still be covered by the following Claims.

Claims: C L A I M S 1. A cutting tool with replaceable blade inserts comprising a body having distal and proximal sides, said body having a shank projecting from said body proximal side, said shank designed to be rotated around a rotatory axis, wherein said body has two substantially parallel grooves on said body distal side, wherein two blade inserts are provided, each with a cutting edge and an opposing blunt edge, one of said two blade inserts is inserted into one of said two substantially parallel grooves, and the other one of said two blade inserts is inserted into the other one of said two substantially parallel grooves, so that the cutting edge and the opposing blunt edge of each one of said two blade inserts protrudes from said body perpendicularly to said rotatory axis, wherein the cutting edge of one of said two blade inserts faces the blunt edge of the other one of said two blade inserts, and wherein the cutting edge of each one of said two blade inserts further protrudes relative to the blunt edge of the other one of said two blade inserts. 2. The tool according to Claim 1 , wherein said body is cylindrically shaped. 3. The tool according to Claim 1 , wherein said body is provided with two opposite concavities. 4. The tool according to Claim 1 , wherein said body has 180° symmetry around said rotatory axis. 5. The tool according to Claim 1 , wherein said tool is used installed in an automated machine that provides rotatory motion to said cutting tool, along its symmetry axis. 6. The tool according to Claim 1 , wherein a broad notch is carved inside the cutting tool's body, in order to accommodate the blade inserts. 7. The tool according to Claims 3 and 6, wherein said broad notch is carved from one said concavity to the other. 8. The tool according to Claim 6, wherein said broad notch is provided with two substantially parallel deeper grooves, along the bottom of said broad notch in two opposing sides, into which the blade inserts are inserted. 9. The tool according to Claim 8, wherein a wedge is positioned between said blade inserts. 10. The tool according to Claim 1 and 8, wherein a passage is drilled along the body, perpendicular to said grooves, and opens into said grooves. 11. The tool according to Claim 2 and 8, wherein a passage is drilled along the body's diameter and perpendicular to said grooves, and opens into said grooves 12. The tool according to Claim 11 , wherein said passage is cylindrical. 13. The tool according to Claim 12, wherein through said passage, a metal pin is threaded, fully inserted. 14. The tool according to Claim 1 , 11 and 6, wherein near each one of the external openings of said passage, an additional bore is provided, drilled parallelly to said passage and passing up to the proximal side-wall of said broad notch. 15. The tool according to Claim 14, wherein said bore is provided with internal threading. 16. The tool according to Claim 1 , wherein said two blade inserts are made of hard metal. 17. The tool according to Claim 16, wherein said blade inserts are made of tungsten carbide. 18. The tool according to Claim 1 , wherein said two blade inserts has similar profiles that can be selected from a variety of profiles. 19. The tool according to Claim 1 , wherein each blade insert is provided with a recess designed to accommodate said pin portion exposed in the groove. 20. The tool according to Claim 1 and 13 and 9, wherein each blade insert is provided with a bore, and a screw is screwed through said bore in said body, and through said bore in said blade insert and fastened against the wedge. 21. The tool according to Claim 1 , wherein said cutting tool's body is metallic. 22. The tool according to Claim 1 , wherein said blade inserts are replaced when said cutting edge becomes blunt. 23. A cutting tool with replaceable blade inserts comprising a body having distal and proximal sides, said body having a shank projecting from said body proximal side, said shank designed to be rotated around a rotatory axis, said body having a rod projecting 5 from said body distal side along said rotatory axis, wherein said body has two substantially parallel grooves on said body distal side, wherein two blade inserts are inserted into said grooves, each one of said blade inserts is inserted into a groove, so that the cutting edge and the opposing blunt edge of each one of said two blade 10 inserts protrude from said body, wherein the cutting edge of one of said two blade inserts faces the blunt edge of the other of said two blade inserts, and wherein the cutting edge of each one of said two blade inserts further protrudes from the blunt edge of the other of said two blade inserts, wherein each one of said two blade inserts is 15 further held in position by means of a restrainer mounted on said rod. 24. The tool according to Claim 23, wherein said body is a plate that resembles a rectangle with chopped corners, with two opposing 20 concavities on its short sides. 25. The tool according to Claim 23 and 24, wherein said body is metallic. 25 26. The tool according to Claim 23 and 24, wherein said rotatory axis preferably passing through the body's center of mass. 27. The tool according to Claim 23, wherein said shank is a shaft designated to be installed in an automated machine that provides 30 rotatory motion to said cutting tool. 28. The tool according to Claim 23, wherein an external threading is provided on the distal end of said rod. 29. The tool according to Claim 23 and 24, wherein said two 5 substantially parallel grooves are substantially parallel to the longer sides of said rectangular plate. 30. The tool according to Claim 23 and 24, wherein two bores are drilled through said plate, parallel to said shank, and open into said 10 grooves. 31. The tool according to Claim 30, wherein said two bores are provided with internal threading to allow a screw to be screwed in. 15 32. The tool according to Claim 31 , wherein said screw is Elen-type screw. 33. The tool according to Claim 23, wherein said two blade inserts are made of a hard metal. 20 34. The tool according to Claim 33, wherein said two blade inserts are made of tungsten carbide. 35. The tool according to Claim 23, wherein said two blade inserts has 25 similar profiles that can be selected from a variety of profiles. 36. The tool according to Claim 23, 31 and 32 wherein each blade insert is provided with a recess, said recess is designed to accommodate the project portion of said screw. 30 37. The tool according to Claim 23, wherein said restrainer is in the form of an annular ring with two substantially parallel grooves, said parallel grooves directed at said cutting tool's body. 38. The tool according to Claim 23 and 37, wherein said blade inserts are each provided with a recess that is predesigned to fit into said grooves on said restrainer. 39. The tool according to Claim 23 and 37, wherein said restrainer circumscribes the distal side of said rod. 40. The tool according to Claim 23 and 37, wherein the cleft between said grooves on said restrainer is smaller than the cleft between said grooves on the body, so that said blade inserts are tilted with respect to said body and incline towards said rod. 41. The tool according to Claim 23, wherein attached to the restrainer, is a ball-bearing circumscribing said rod, and mounted from said rod distal end. 42. The tool according to Claim 41 , wherein the outer diameter of said ball-bearing is larger than said restrainer diameter. 43. The tool according to Claim 23, wherein a nut is screwed on the distal end of said rod. 44. The tool according to Claim 23 and 41 , wherein a nut is screwed on the distal end of said rod. 45. The tool according to Claim 23, wherein said blade inserts are replaced when said cutting edge become blunt. 46. The tool according to Claim 23, wherein said restrainer is further provided with two projecting walls, wherein the inner surface of each wall is tilted in a predetermined angle so that said inner surface is substantially parallel and adjacent to each of said blade's plane. 47. The tool according to Claim 46, wherein each of said projecting walls is provided with two protrusions that fit into corresponding recesses provided on said body.

Inventors: SPECTOR GAVRIEL, SPECTOR, GAVRIEL
Applicants: DIMAR LTD, SPECTOR GAVRIEL, DIMAR LTD., SPECTOR, GAVRIEL
Application year: 2000
Main classification: B23C5
IPC codes: B27G13