PRECISION ECCENTRIC CLAMP FOR CORDS AND THE LIKE

Abstract: A clamping device consists of a frame body (1) having a first cylindrical through bore (2) into which a cylindrical roller (3) is fittingly mounted with possibility of rotary movement, the roller (3) having on its periphery an eccentric groove (9) of semi-circular shape in cross section with radius corresponding to the radius of the cord (6) to be clamped, a second through bore (7a), with axis tangent to the circumference of said first bore and perpendicular to generating line of the first bore, situated directly opposite to the eccentric groove (9), and having the diameter corresponding to the diameter of the cord (6) to be clamped and the frame body having a third bore (7b) coaxial with the second bore (7a), and the first bore having a cavity (10), the cross section of which is of a semi-circular shape with radius corresponding to the radius of the cord (6), situated directly opposite to said eccentric groove (9), constituting an arc, the generating line of which is at one its end tangent to the circumference of the first bore (2) and at its other end, tangent or near tangent to the third bore (7b), the radius of the arc generating line (11) being slightly smaller than the radius of the first bore (2) and the centre of the arc generating line being situated in the surface of the half circle made by the circumference of the first bore (2) and its axis perpendicular to the axis of the second and third bore (7a, 7b) where said half circle being adjacent to said second bore and third (7a, 7b).

Description: Precision eccentric clamp for cords and the likes The object of this invention is a precision, eccentric clamp for cords, ropes, strings, made of threads of natural fibres, plastic, metal and it is particularly suitable for very thin cords twisted from tiny wires. There are known many solutions of clamping devices for cords and the likes, applying friction forces for clamping. In conventional solutions to exert the necessary pressure, screw, lever, cam-lever and wedge mechanisms are applied. None of these constructions makes it possible to realise a simple self-clamping mechanism, enabling to withstand forces equal to the cord limit strength, without causing durable cord deformation. In the most often cases these deformations preclude re-clamping the cord on the section where the cord was once been clamped. In German application No 197 00 193, an eccentric cam clamping mechanism is described, in which, to make a cord loop, two ends of the cord are to be introduced into a bore within the base element in which, In a hexagonal cavity, a guiding element with respective hexagonal external shape, is mounted, the guiding element having a first . large through bore in which the clamping element is placed, and having a second bore which is coaxial with the bore for the cords in the base element and tangent to the large bore in the guiding element, the clamping element being in the shape of a roller with an eccentric grove on its circumference , the grove being of rectangular shape in cross section, large enough to accommodate two cords to be clamped, and having a knurled, flat bottom. Turning the clamping element causes locking both ends of cord thus making loop. Because of the fact that both ends of cord making loop must pass through one bore and there they are clamped by the same eccentric roller, makes it impossible to press them symmetrically and even may prevent to clamp one of the cord at all . Besides, clamping by a flat, knurled bottom of the eccentric roller, causes local wear and distortions of the cord , especially if it is made of twisted threads or wires. It is an object of this invention to provide a simple clamping device which could create maximum locking pressure upon the cord without causing its deformation and wear down. The clamping device according to the present invention consists of a frame body having a first cylindrical through bore into which a cylindrical roller is fittingly mounted with possibility of rotary movement, the roller having on its periphery an eccentric groove of semi-circular shape in cross section , with radius corresponding to the radius of the cord to be clamped, the depth of the grove changing from minimum zero to maximum slightly bigger than the cord diameter, the frame body having a second bore, with axis tangent or near tangent to the circumference of said first bore and perpendicular to the generating line of the circumference of the first bore, the second bore being situated directly opposite to the eccentric groove, and having the diameter corresponding to the diameter of the cord to be clamped, said frame body having a third bore, with the axis coaxial or nearly coaxial to the second bore and with the same diameter as the second bore, both second and third bore having an inlet and outlet portions, the first bore having a cavity situated directly opposite to said eccentric groove, being of a semi-circular shape in cross section with radius corresponding to the radius of the cord to be clamped, the cavity constituting an arc, the generating line of the arc is at one its end tangent to the circumference of the first bore and at its other end , is tangent or near tangent to the outlet portion of the third bore, the radius of the generating line of the arc being slightly smaller than the radius of the first bore and the centre of the generating line of the arc being situated on the surface of the half circle made by the circumference of the first bore and its axis parallel to the axis of the second and third bore where said half circle being adjacent to said second and third bore. Mounting in the first bore two rollers, which are rotated independently either in the same direction or in opposite directions, make it possible to create two cord loops , either at the same side of the frame body, or at opposite sides of the frame body. The eccentric groove forces the cord into the cavity inside the frame body encompassing the cord on the whole length of the cavity arc, thus creating first clamping action . Further clamping action, that means self-clamping action, is created under actions of those forces which pull the cord out of the frame body . Owing to the semicircular shape of the eccentric groove on the roller and the same shape of the cavity in the frame body with radii corresponding to the radius of the cord to be clamped , neither deformation nor wear-down of the cord occurs, no matter how big the clamping pressure is exerted upon the cord. The object of this invention is illustrated in, but not limited to, the preferable embodiment, on the accompanying drawing , on which Fig. 1 illustrates the clamping device in pictorial view with one end of cord free, Fig. 2 is the same view but with cord loop already made, Fig.3 is an exploded view of the device according to the invention , Fig. 4 is a full section of the device with one roller, illustrating the state after the cord has been inserted, Fig . 5 is a cross section along the line B - B on Fig. 4, Fig. 6 is a full section of the device with one roller, illustrating the state after the cord has been clamped , Fig. 7 is a cross section along line B - B on Fig. 6, Fig. 8 is a full section of the device with two rollers working in synchronous , illustrating the state after the cords have been clamped, Fig. 9 is a cross section along line B - B on Fig 8, Fig. 9 is a full section of the device with two rollers working in opposite directions, illustrating the state after the cords have been clamped and Fig 1 1 is a cross section along the line B - B on Fig 1 0 The clamping device according to present invention consists loo of a frame body 1 having a first cylindrical though bore 2 into which a cylindrical roller 3 is fittingly mounted with possibility of rotary movement, but with no possibility of any axial movement, owing to lever 8, which encompasses the frame body 1 and is fixed to the roller 3 in any manner (not shown) , the roller having on its 105 periphery an eccentric groove 9 of semi-circular shape in cross section with radius corresponding to the radius of the cord 6 to be clamped, the depth of the grove changing from minimum zero to maximum slightly bigger than the cord diameter, the frame body 1 having a second through bore 7a with axis tangent or near tangent no to the circumference of said first bore 2 and perpendicular to the generating line of the circumference of the first bore 2, situated directly opposite to the eccentric groove 9, and having the diameter corresponding to the diameter of the cord 6 to be clamped, said frame body 1 having a third bore 7b with axis coaxial or nearly ιi5 coaxial to the axis of the second bore 7a, and with the same diameter as the second bore 7a, both second and third bore having an inlet and outlet portions, in accordance with the direction of pulling forces acting upon the cord 6 when the latter is passed through the clamp Said first bore 2 has a cavity 10, of a semi- 120 circular shape in the cross section , with radius corresponding to the radius of the cord 6 to be clamped Said cavity ip_ is situated opposite to said eccentric groove 9 , and constitutes an arc, the generating line 1 _ of the arc is ,at one its end, tangent to the circumference of the first bore 2 and at its other end , is tangent or 125 near tangent to the outlet portion of the third bore 7b The radius of said generating line 1J_ of the arc is slightly smaller than the radius of the first bore 2 and the centre of the cavity arc generating line Y\_ is situated on the surface of the half circle made by the circumference of the first bore 2 and its axis parallel to the axis of DO the second bore 7a. and the third bore 7Jb, where said half circle being adjacent to said second bore 7b and third bore 7b. On the outer portion of the frame body 1 a threaded bore 4 is situated into which a special ending 5 of the cord 6 is screwed-in . To make a loop , the other, free end of cord 6 is to be passed 135 through the second and third bore 7a and 7b_, then is to be locked by turning the lever 8. and roller 3. in the direction of the arrow on Fig. 4. Under pressure of the eccentric groove 9 cord 6 is deflected and fills the cavity 1_0 , creating first stage of frictional locking of the cord 6 between cavity 1_0 and eccentric groove 9. Second stage HO of the frictional locking occurs under action of pulling force P_ in cord 6 (Fig. 6) which causes self-turning of the roller 3 thus exerting further pressure upon cord 6 and in consequence further locking of the cord 6, this time in automatic self-locking manner, with the strength growing in proportion to the to pulling force P.. 145 Owing to the semicircular shape of the eccentric groove 9 on the of the roller 3 and the arc cavity 10. in the frame body with radii corresponding to the radius of the cord 6 to be clamped , no deformation and no wear-down of the cord diameter and cord circular shape occurs, no matter how big the clamping force is 150 exerted. Within the scope of the invention, modifications can be made, consisting of application of two rollers in tandem, mounted within the frame body, acting independently, which makes it possible to create two cord loops either acting in parallel at one side(Fig.8 and 155 9) or acting oppositely at opposite sides of the frame body. (Fig . 1 0 and 1 1 ) . The clamping device according to present invention is particularly suitable to very small, precision embodiments with application in dentistry for removing dental bridges and prosthesis 160 without impairing existing ceramic parts of the dentistry appliances.

Claims: Claims 1 . A precision eccentric clamp for cords and the likes consisting of a frame body (1_) having a first cylindrical through bore (2) into which a cylindrical roller (3) is fittingly mounted with possibility of rotary movement, the roller (3) having on its periphery an eccentric groove (9), the frame body (IJhaving a second bore (7a) , with axis tangent or near tangent to the circumference of said first bore (2) and perpendicular to the generating line of the circumference of the first bore (2), situated directly opposite to the eccentric groove (9) and having the diameter corresponding to the diameter of the cord (6) to be clamped, said frame body (1) having a third bore (7b) with the axis coaxial or nearly coaxial to the second bore (7a) and with the same diameter as the second bore (7a), both second and third bore having an inlet and outlet portions, characterised by that, that said eccentric grove (9) is of semi circular shape in cross section , with the radius corresponding to the radius of the cord (6) to be clamped, and with the depth changing from minimum zero to maximum slightly bigger than the cord diameter, and by that, that the first bore (2) has a cavity ( 10) ,of a semi-circular shape in cross section with radius corresponding to the radius of the cord (6) to be clamped, said cavity being situated directly opposite to said eccentric groove (9), constituting an arc, the generating line ( D of which is, at one its end, tangent to the circumference of the first bore (2) and at its other end, is tangent or near tangent to the outlet portion of the third bore (7b), the radius of the arc generating line (ID being slightly smaller than the radius of the first bore (2) and the centre of the arc generating line (ID being situated on the surface of the half circle made by the circumference of the first bore (2) and its axis parallel to the axis of the second and third bore (7a and 7b) where said half circle being adjacent to said second and third bore (7a. and 7b) . 2. A precision eccentric clamp according to claim 1 , characterised by that, that it has two rollers in tandem working independently. 3. A precision eccentric clamp according to claim 2, characterised by that, that said two rollers work in the same direction. 4. A precision eccentric clamp according to claim 2, characterised by that, that said two rollers work in opposite directions.

Inventors: SZCZEPANCZYK JERZY, SZCZEPA&NACUTE
Applicants: SZCZEPANCZYK JERZY, SZCZEPA&NACUTE
Application year: 2000
Main classification: F16G11
IPC codes: F16G11