Radial miter saw for sections

Abstract: A radial miter saw for sections, comprising a base (2) for supporting parts on which an upper platform (3) is mounted, the platform being able to turn in two directions and being provided with a reference abutment (4) and with a cutting slot (5), and a working head (6) which is composed of a circular blade (7) actuated by a corresponding motor assembly (8) and supported so as to be slideable between a position which is proximate to the abutment and a position which is distal with respect to it at the end of a cantilevered supporting arm (9), wherein the arm is constituted by a straight segment (10) of a hollow section which is slidingly engaged, with a single degree of freedom, on a carriage (11) which is mounted at the upper end of a support (12) which protrudes from said rotating platform (3) and is provided with means (13) for two-dimensional position adjustment and with means (14) for locking the position.

Description: The present invention relates to a radial miter saw for sections. Conventional miter saws, termed radial because they can work in a radial direction, have long been used by operators in the field in order to cut sections of different kinds on-site. These machines essentially comprise a head on which a circular saw, driven by a corresponding motor, is mounted; in turn, this circular saw is articulately supported on a frame acting as an actual base for the miter saw and as a worktable on which the sections to be cut are rested. The heads of conventional miter saws are, as above-mentioned, provided with an articulation in order to be able to cut the sections according to deifferent angles in space and are mounted so as to slide back and forth with respect to the position of the operator on strong horizontal guides, known as feed rods, in order to be able to perform cuts of a given depth. Further, in compliance with applicable accident-prevention standards, they must be provided with blade guards so as not to access the cutting region of the blade with one's hands even unintentionally. In practice, the spatial movement of the heads provides for a combination of possible movements ranging from straight-line translatory motion on the feed rods back and forth with respect to the operator, to rotation with a bilateral diagonal tilt of the blade, to swinging about a vertical axis which passes substantial at the initial region of the feed rods, to an upward and downward movement of the heads with respect to the base. However, the shape of the articulations and most of all the possible extension of the feed rods limits the operating capabilities in conventional miter saws. Essentially, the sections on which these conventional machines can work must have dimensions and cross-sections which are limited by the active stroke that can be achieved with the heads on the feed rods, which if they were excessively long would cause the cantilever of the head, and therefore its weight, to assume values which would unacceptably reduce the precision of the cuts due to the onset of flexing and swaying, by the rotation angle that the feed rods can assume, and by the useful gap between the blade and the surface for supporting the sections, which allows so-called "butt" cutting of the sections. In summary, the maximum dimensions of the sections must be contained to medium to low values, and conventional miter saws therefore have limited operating capabilities if acceptable cutting precision is required. Moreover, the feed rods have shown, in some cases, high friction, causing early signs of seizure of the elements which, by coupling, allow the sliding of the head thereon: the gradual, even if slow, deterioration of the elements also affects the cutting precision. A saw mechanism with miter box and pivoting arm is disclosed in US-A-4 537 105. The aim of the present invention is to solve the above-noted problems of the prior art, providing a radial miter saw for sections which allows to work on larger sections than allowed by conventional miter saws, allows to perform butt cutting, at the same time has a simple structure which can be easily accessed for ordinary and extraordinary maintenance and has substantially modest dimensions and weights, does not cause seizures and maintains its cutting precision unchanged over time, at the same time working in maximum safety for users in any condition. This aim and other objects are achieved by a radial miter saw according to the invention, which has the features set forth in claim 1. Further characteristics and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment of a radial miter saw for sections, illustrated only by way of non-limitative example in the accompanying drawings, wherein: Figure 1 is a front perspective view of the radial miter saw according to the invention; Figure 2 is a rear perspective view of the miter saw of Figure1; Figures 3 and 4 are, respectively, a front perspective view and a rear perspective view, showing only the working head of the miter saw according to the invention without the base, and respectively showing the blade in a rotated position and the blade in a straight position; Figure 5 is a schematic side view, in phantom lines, of the working head alone, with the blade in the rotated position; Figure 6 is another side view, in phantom lines, of the guards with which the blade is provided; Figure 7 is an exploded perspective view of the components of the arm of the miter saw; Figure 8 is a perspective view of the miter saw according to the invention in a second embodiment provided with a part supporting surface arranged above the arm; Figure 9 is a schematic side view, in phantom lines, of the miter saw according to the invention illustrated in Figure 8. With reference to the above figures, 1 designates a radial miter saw for sections which comprises a base 2 for supporting parts on which an upper platform 3 is mounted; the platform can rotate in two directions and is provided with a reference abutment 4 and with a cutting slot 5. The abutment 4 is fixed to the base 2 by means of two posts (not visible in the drawings) passing through corresponding arc-like slots 3a formed bilaterally in the platform 3. The miter saw 1 is further composed of a working head 6, which is in turn composed of a circular blade 7 which is actuated by a corresponding motor assembly 8 and is supported so as to slide between a position which is proximate to the reference abutment 4 and a position which is distal thereto at the end 9a of a cantilevered supporting arm 9. The arm is constituted by a straight segment 10 of a hollow section, which is slidingly engaged with a single degree of freedom, essentially so as to slide only axially, on a carriage 11 which is mounted at the upper end of a support 12 which protrudes from the platform 3; this support is provided with means 13 for two-dimensional position adjustment and with means 14 for locking the position once it has been reached. Means for the rotary articulation of the head 6 with respect to the arm 9 about an axis A which is perpendicular to the arm 9 are interposed between the working head 6 and the end 9a of the arm 9. The working head 6 is provided with means 16 and 17 for constantly protecting the integral portion of the blade in any configuration thereof, in addition to the fixed upper housing 18. The section segment 10 that constitutes the arm 9 has a C-shaped cross-section in which the opening 10a faces downwards. The support 12 is constituted by a prism-shaped block 19 which is coupled to the platform 3 or, more specifically, to a further block 19a which protrudes rigidly from the platform; the block 19 is affected by an engagement seat 20, which can be fixed angularly by way of the locking means, for the head of a pivot 21 which is transversely rigidly coupled to the base of a post 22 for supporting the carriage 11. Articulation hinge means 23, adapted to allow the inclination of the arm 9 on a vertical plane, and elastic return means 24 are interposed between the carriage and the upper end of the post 22. The post 22 is further provided with a stop element 22a provided with an abutment tooth 22b and whose position can be finely adjusted; the stop element is rigidly coupled to the rotating platform 3, and the post is further provided with an eyelet 22c which is formed in the rear region and in which it is insertable, in a finely adjustable way, an additional stop tooth 22d which affects a switch 22c which acts on the power supply of the motor assembly 8. The angular locking means 14 are constituted by a through threaded key 25 which is slideable transversely in a curved slot 26 formed in the block 19 and is screwable transversely in the head of the pivot 21. The hinge means 23 are constituted by two pairs of brackets 27 and 28 which protrude respectively from the lower face of the carriage 11 and from the facing upper end of the post 22 and mutually overlap; the brackets are mutually connected by means of an ordinary transverse articulation pin 29 which is inserted in aligned eyelets formed in said pairs of brackets 27 and 28. The elastic return means 24 are constituted by two mutually parallel traction springs 30 whose respective ends are rigidly coupled to the block 19 and to further second brackets 31 which protrude downwards from the lower face of the carriage 11; elements 32 for stopping the rotation of the arm 9 on a vertical plane are provided between the carriage and the post 22 and are constituted by a flat pawl 33 in which one end is rotatably articulated at 34 to the upper end of the post 22 and the opposite end is provided with at least one pair of abutment teeth 33a and 33b having different heights, which alternatively act as lower abutments, at different levels, which can be alternated by means of the rotation of the pawl 33, for said arm 9. The means 15 for the rotary articulation of the head 6 with respect to the arm 9 are constituted by a ledge-like bracket 35 which protrudes from the distal end 9a of the arm 9 that is directed towards the blade 7 and is affected by two circular converging slots 36 which are arranged bilaterally to the rotation axis A for the rightward and leftward guiding of two pins engaged therein (not shown in the drawings) which protrude from the body of the motor assembly 8. The means 16 and 17 for the integral protection of the blade 7 are constituted by a series of circular sectors 38 which can be arranged in a fan-like configuration in contact on the parts and mutually interpenetrate telescopically and retractably in a gradual way, in proportion to the penetration of the blade 7 in the parts. The sectors 38 are rotationally pivoted at 39 coaxially to the blade 7 and are activatable in a protection configuration alternatively to a parallel semicircular monolithic element 40 which is normally retained in the raised inactive position by hook means 41 which can be disengaged manually or automatically by the sectors 38 when they reach a configuration which fully exposes the blade 7. The hook means 41 are constituted by a detent 42 which can be inserted, in the configuration in which the semicircular element 40 does not intervene, in a retention recess 40a formed in the handle of the element. At least the first one of the circular sectors 38 is provided with a feeler 43 for constant contact with the parts. Finally, the base 2 is bilaterally provided with supporting means 44 for modular surfaces for extending the part supporting surface; these surfaces are constituted by respective pairs of rods 45 mounted horizontally so as to be extractable from the base 2 and can be retractably stored below it when not in use. In a second embodiment of the radial miter saw 1, an additional surface 46 for resting the parts to be cut is provided above the working head 6 and is rigidly coupled thereto; the surface 46 is crossed by a slot 46a which lies at the plane of arrangement of the blade 7 and through which the upper portion of the blade 7 protrudes. The operation of the invention is as follows: when it is necessary to cut a section, the section is usually arranged in abutment against the reference abutment 4. If the cut to be performed is of the so-called "butt" type, the operator pulls the working head 6 towards him and raises the arm 9 with respect to the platform 3; then, by overcoming the return action of the springs 30, he turns the post 22 towards the platform until it abuts against the stop element 22b, which has been set beforehand. The operator then starts the motor assembly 8 and, by lowering the blade 7 onto the part, performs the butt cut as required, biting into the part from its rear region, i.e. starting from the outer region towards the reference abutment 4. With the miter saw 1 it is also possible to perform other cuttings of sections in all spatial directions: by turning the working head 6 about the axis A (see also Figure 4) it is in fact possible to perform longitudinal cuttings of very long sections. In order to prevent the blade, in this configuration, from damaging the platform 3 at the lower end of its stroke because it is no longer aligned with the working slot 5, in which instead it normally penetrates when it is parallel to the arm 9, the operator moves the pawl 33 so as to place the higher tooth 33b under the arm 9, so that when the operator performs the cut by pushing the blade towards the platform 3 the arm 9 abuts against the tooth 33b, whose height is adequately calculated so as to keep the blade 7 raised from the platform 3, even if by only a few millimeters. Another operating possibility is further obtained by acting on the key 25; by loosening the key it is possible to move the working head 6, tilting it laterally on either side; this allows to perform oblique cuts. The second embodiment of the radial miter saw 1 is provided with an upper surface 46 for supporting very long sections to be cut: this version is functionally equivalent to the preceding one but cheaper to provide and is proposed as an alternative to the more complete and expensive one in which the head 6 can rotate about the axis A. In all cases, the particular embodiment of the arm 9, which is common to both embodiments, allows to work with maximum ease in sliding and precision: the carriage 11 in fact slides within the hollow section 10 without appreciable plays and with minimal friction. Accordingly, the working head 6 is therefore guided perfectly without swaying even when the arm 9 and the post 22 consecutively reach the maximum outreach proximate to the operator with respect to the abutment 4. Moreover, the sectors 38, which are also common to both versions, protect the blade 7 in any position that it assumes with respect to the part to be cut; the telescopic arrangement by means of which they are articulated allows the gradual reaction of one sector into the next as the penetration of the blade 7 increases, without however ever exposing it and in practice preventing the operator or anyone else from arranging their hands proximate to it: the feeler 43 in fact keeps constant contact with the part being cut. Even if these sectors 38 were forced to retract completely in case of very deep cuts, i.e. of very tall sections, the last one of the sectors would strike the detent 42, disengaging it automatically from the retention recess 40a and making the semicircular element 40 descend into an alternative protective position. Once the above-described extreme condition has ceased, the operator, by lifting the blade from the part and thus allowing the sectors 38 to extend again in a fan-like arrangement, can disengage the element 40, locking it again in the raised position by means of the detent 42. It is noted that the particular structure of the arm 9, combined with the post 22, allow the head 6 of the miter saw 1 to reach, in the extended configuration, outreaches which are absolutely unusual with respect to known miter saws. When the arm 9 is fully lowered towards the platform 3, the stop tooth 22d is inserted in the eyelet 22c and affects the switch 22e, which in this configuration allows to switch on and off the motor assembly 8 by means of two on-off buttons located on a handle 47 which is associated with the housing 18. Moreover, the possibility to provide for the rightward or leftward rotation of the head 6 by up to 90° on each side allows the miter saw to perform cuts even on very long sections; for these sections, the base 2 is supplemented by modular extension surfaces, resting them on the supporting means 44 which are extractable for this purpose. In practice it has been observed that the above-described invention achieves the intended aim. The invention this conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept. All the details may further be replaced with other technically equivalent ones. In practice, the materials employed, as well as the shapes and the dimensions, may be any according to requirements without thereby abandoning the scope of the protection of the appended claims. The disclosures in Italian Patent Application No. MO99A000056 from which this application claims priority are incorporated herein by reference. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims: A radial miter saw for sections, comprising a base (2) for supporting parts on which an upper platform (3) is mounted, said platform (3) being able to turn in two directions and being provided with a reference abutment (4) and with a cutting slot (5), and a working head (6) which is composed of a circular blade (7) actuated by a corresponding motor assembly (8) and supported so as to slide between a position which is proximate to the abutment (4) and a position which is distal with respect to it at the end (9a) of a cantilevered, straight supporting arm (9) which is slidingly engaged, with a single degree of freedom, on a carriage (11) mounted at the upper end of a support (12) protruding from said rotating platform (3), said support (12) comprising position adjustment means (13), locking position means (14) and a post (22) for supporting said carriage (11), said post (22) being pivoted (21) at its base so as to be turnable towards the platform (3) by overcoming a return action of elastic return means (24), characterized in that it further comprises articulation hinge means (23), interposed between the upper end of said post (22) and said carriage (11), which allow inclination of said arm (9) on a vertical plane, with stop elements (32) for the downward stopping of the rotation of said arm (9) interposed, said hinge means (23) being constituted by two pairs of brackets (27, 28) which protrude respectively from the lower face of said carriage (11) and from the upper facing end of said post (22), mutually overlap and are mutually connected by way of a mutual transverse articulation pivot (29) which is inserted in aligned eyelets formed in said pairs of brackets (27, 28), said arm (9) being constituted by a hollow section segment (10), and said position adjustment means (13) being provided so as to provide a two-dimensional position adjustment. The radial miter saw according to claim 1, characterized in that means (15) for the rotary articulation of the head (6) with respect to said arm (9) about an axis (A) perpendicular to said arm (9) are interposed between said working head (6) and said end (9a) of the arm (9). The radial miter saw according to claim 1, characterized in that said working head (6) is provided with means (16, 17) for the constant protection of the integral portion of the blade (7) in every configuration thereof. The radial miter saw according to claim 1, characterized in that said section segment (10) has a C-shaped cross-section in which the opening faces downwards. The radial miter saw according to claim 1, characterized in that said support (12) is constituted by a prism-shaped block (19) which is rigidly coupled to said platform (3) and is provided with an engagement seat (20), which can be angularly fixed with said locking means (14), for the head of a pivot (21) which is transversely rigidly coupled to the base of a post (22) for supporting said carriage (11). The radial miter saw according to claim 5, characterized in that said angular locking means (14) are constituted by a threaded through key (25) which is slideable transversely in a curved slot (26) which is formed in said block (19) and is screwable transversely in said head of the pivot (21). The radial miter saw according to any of the preceding claims, characterized in that said elastic return means (24) are constituted by two traction springs (30) which are mutually parallel and whose ends are rigidly coupled respectively to said block (19) and to additional second brackets (31) which protrude downwards from the lower face of said carriage (11). The radial miter saw according to claim 6, characterized in that said stop elements (32) for stopping rotation of the arm (9) on a vertical plane are constituted by a flat pawl (33) in which one end is articulated (34) to the corresponding upper end of said post (22) and the opposite end is provided with at least one pair of abutment teeth (33a, 33b) having different heights which can be alternatively arranged below said arm (9) after turning said pawl (33). The radial miter saw according to the preceding claims, characterized in that a finely adjustable element (22d) for stopping the rotation of said post (22) towards said platform (3) is interposed between said post (22) and said platform (3). The radial miter saw according to claim 2, characterized in that said means (15) for the rotary articulation of the head (6) with respect to the arm (9) are constituted by a ledge-like bracket (35) which protrudes from the distal end (9a) of said arm (9) that is directed towards the blade (7) and is provided with two converging circular slots (36) which are arranged bilaterally with respect to the rotation axis (A) for the rightward and leftward guiding of two pins which engage therein and protrude from the body of said motor assembly 8) for actuating the blade (7). The radial miter saw according to claim 3, characterized in that said means (16, 17) for the integral protection of the blade (7) are constituted by a series of circular sectors which can be arranged in a fan-like configuration in contact on the parts and telescopically and retractably interpenetrate gradually and proportionally to the penetration of the blade (7) in the parts, said sectors (38) being rotationally pivoted coaxially to said blade (7) and being activatable in the protection configuration alternatively with respect to a parallel semicircular monolithic element (40) which is normally retained in the raised inactive position by hook means (41) which can be disengaged manually or automatically by said sectors (38) if they reach a configuration in which the blade (7) is fully exposed. The radial miter saw according to claim 11, characterized in that at least the first one of said circular sectors (38) is provided with a feeler (43) for constant contact with the parts. The radial miter saw according to the preceding claims, characterized in that said base (2) is bilaterally provided with supporting means (44) for modular surfaces for extending the part supporting surface. The radial miter saw according to claim 13, characterized in that said supporting means (44) are constituted by respective pairs of rods (45) which are fitted horizontally and so that they can be extracted from said base (2) and can be retractably stored below it in the inactive configuration. The radial miter saw according to the preceding claims, characterized in that said head (6) is provided, in an upward region, with a second part supporting surface (46) which is crossed by a slot (46a) formed on the vertical plane of arrangement of said blade (7) for the passage of an upper portion of said blade (7). The radial miter saw according to the preceding claims, characterized in that in the so-called butt cutting of sections, said head (6) moves the blade (7) so as to bite into the sections from the rear, i.e. by translatory motion on said arm (9) from the outside towards said reference abutment (4). The miter saw according to claim 1, characterized in that said reference abutment (4) is supported on the base (3) by corresponding vertical posts which pass at corresponding circular-arc slots (3a) which are formed bilaterally in said platform (3).

Inventors: TOMESANI GIULIANO
Applicants: TOMESANI GIULIANO
Application year: 2000
Main classification: B23D45
IPC codes: B23D45, B27G19, B27B5