Shaft machining anti-vibration device

Abstract

An anti-vibration device for the machining of a shaft includes a first fixed ring intended to be kept inside a shaft by a shoulder, the anti-vibration device including: at least one first external groove and at least one first external seal for forming at least one contact with the internal surface of the shaft; at least one first internal circumferential groove and at least one first internal seal for forming at least one contact with the external surface of the bar; an internal circumferential cavity that is able to cause the circulation of a fluid arriving through a first duct and leaving through a second duct, the first duct and second duct passing through the radial thickness of the anti-vibration device, the internal circumferential cavity making it possible to realize a vibration-damping function when a fluid passes through it.

Claims

1. An anti-vibration device for machining a hollow shaft, comprising a first element constructed and arranged to be maintained at least partially within the hollow shaft in a fixed position in relation to the hollow shaft and constructed and arranged to permit the guiding of a guide bar to move axially within the hollow shaft, the first element comprising: at least one first mechanical vibration damper at an external periphery of the first element in relation to an internal surface of the hollow shaft and in contact with the internal surface; at least one second mechanical vibration damper arranged at an internal diameter surface of the first element in relation to an external surface of the guide bar and in contact with it the external surface; an internal circumferential cavity configured to circulate a fluid arriving via a first duct and exiting via a second duct, the first and second ducts passing through a radial thickness between the external periphery of the first element and the internal diameter surface of the first element, the internal circumferential cavity forming a hydraulic damper when a pressurized lubricating fluid flows through the first element.

2. The anti-vibration device for machining a hollow shaft according to claim 1, wherein the first element is a first collar held fixed axially in relation to the hollow shaft by means of a shoulder, the anti-vibration device comprising: at least one first external groove and at least one first external seal adapted to cooperate with the first external groove and forming the first mechanical vibration damper; at least a first internal circumferential groove and at least one first internal seal adapted to cooperate with the first internal groove and forming the second mechanical vibration damper.

3. The anti-vibration device for machining a hollow shaft according to claim 2, wherein the first internal circumferential groove and a second internal circumferential groove are each located close to the extremities of the first collar.

4. The anti-vibration device for machining a hollow shaft according to claim 3, wherein the internal circumferential cavity extends longitudinally between: a first extremity in proximity to the first internal circumferential groove; a second extremity in proximity to the second internal circumferential groove.

5. The anti-vibration device for machining a hollow shaft according to claim 4, wherein the first duct comprises: a first elbowed opening permitting the passage of a fluid from the exterior of the anti-vibration device towards the internal circumferential cavity, the first elbowed opening comprising a longitudinal opening extending along the exterior surface of the first collar and a radial extension leading into the internal circumferential cavity in proximity to the first extremity of the internal circumferential cavity.

6. The anti-vibration device for machining a hollow shaft according to claim 5, wherein the second duct comprises: a second elbowed opening permitting the passage of a fluid from the internal circumferential cavity to the exterior of the anti-vibration device, the second elbowed opening comprising a radial opening in proximity to the second extremity of the internal circumferential cavity and a longitudinal prolongation passing through the shoulder so as to lead to the exterior of the anti-vibration device.

7. The anti-vibration device for the machining of a hollow shaft according to claim 1, further comprising a second element constructed and arranged to be maintained at least partially to an exterior of a machining head and in a fixed position in relation to the machining head, the second element comprising: at least a third mechanical vibration damper arranged at an external periphery of the second element in relation to the internal surface of the hollow shaft and making contact with the hollow shaft.

8. The anti-vibration device for machining a hollow shaft according to claim 7, wherein the second element comprises an external groove and an external seal adapted to cooperate with the external groove of the second element and forming the third mechanical vibration damper.

9. The anti-vibration device for machining a hollow shaft according to claim 7, wherein bodies of the first and/or second element are made from polyamide.

Description

BRIEF DESCRIPTION OF FIGURES

(1) Other characteristics and advantages of the invention will become apparent on reading the following detailed description, and referring to the enclosed drawings, which illustrate:

(2) FIG. 1: a fixed collar of the invention comprising a cavity in which a fluid circulates;

(3) FIG. 2: a moveable collar of the invention intended to be attached to a machining head;

(4) FIG. 3: an anti-vibration machining system inserted in a shaft to bore.

DESCRIPTION

(5) FIG. 1 represents an anti-vibration device of the invention comprising a first element forming a fixed collar 10 intended to be secured to a hollow shaft 30 to be bored and lying along longitudinal axis 30A. The shaft 30 is shown in FIG. 3.

(6) The fixed collar 10 has a body 10A lying along a longitudinal axis 10B and having a central opening 10C lying along the said axis and running through the body 10A. The latter is extended by a shoulder 17 on one of its extremities. The shoulder 17 permits the defining of a thrust surface between the fixed collar 10 and one extremity of the shaft to be bored 30. The shoulder 17 of fixed collar 10 thus permits the longitudinal maintaining of the fixed collar 10 in relation to the shaft 30.

(7) The body 10A of the fixed collar 10 comprises one first external groove 12 and at least one external seal 121 adapted to cooperate with the first external groove 12 to form a circumferential contact with the internal surface of shaft 30 when the fixed collar 10 is mounted on the shaft 30.

(8) The fixed collar 10 equally comprises a first internal circumferential groove 11 and at least one first internal seal 110 adapted to cooperate to form a circumferential contact with the external surface of a guide bar 40 of a cutting tool such as machining head 50 shown in FIG. 3. This first groove 11 is located in proximity to one of the edges of the fixed collar 10, i.e. to one of its extremities, preferably opposite the shoulder 17.

(9) The fixed collar 10 comprises a second internal circumferential groove 11 and at least one first internal seal 110 adapted to cooperate to form circumferential contact with the external surface of guide bar 40 of a cutting tool such as machining head 50. This second groove 11 is located in proximity to the other edge of fixed collar 10, i.e. at the opposite extremity to where the first circumferential groove 11 is found, preferably at the extremity of shoulder 17.

(10) The seals 110 and 110 permit forming a contact with a guide shaft 40 and permits the limiting of leaks or the passage of fluid circulating in collar 10.

(11) The opening 10C of fixed collar 10 furthermore comprises an internal circumferential cavity 18 able to circulate a fluid 122 arriving via a first duct 14, 16 and exiting via a second duct 13, 15.

(12) The cavity 18 machined in collar 10 forms a circumferential bath. Because of this, the thickness of the collar over the length of the bath is less than its thickness at its extremities. Thus a certain volume of fluid can circulate in the fixed collar 10 over a given width.

(13) The fluid passing through the collar can only flow through cavity 18 due to the presence: of internal seals 110, 110 stopping the flow of the fluid 122 through the principal opening 10C of the fixed collar 10 and; the external seal 121 stopping the flow of fluid on the external periphery of fixed collar 10 between shaft 30 and the fixed collar 10.

(14) Preferably, the internal and external seals are of a material suited to resist water, oils and lubricants.

(15) Fluid 122 is advantageously a lubrication fluid that can be introduced during machining and notably by the cutting tool that may comprise an opening permitting the injection of the lubricant.

(16) Fixed collar 10 permits the return routing of lubricant 122 towards the exterior of shaft 30 while using its flow inside cavity 18 of the fixed collar 10 as a damper of the vibration generated by the machining operation.

(17) To direct the lubricant 122 to the inside of the cavity 18, the fixed collar comprises openings 16, 14 on its extremity located inside shaft 30. The openings 16, 14 form elbow shaped ducts or lumen 16, 14.

(18) FIG. 1 represents a cross-section of an elbow shaped groove 16, 14 in which a first longitudinal groove leads, on one hand, towards the extremity of the fixed collar 10 and, on the other, towards a radial groove 14 leading into cavity 18.

(19) Thus the lubricant previously injected into the shaft to be bored via an opening (not shown) of the cutting tool 50 may exit by at least a first duct 14, 16 giving onto the hollow cavity 18 of the fixed collar 10 and forming a circumferential cavity 18.

(20) The fixed collar 10 may comprise a plurality of inlets and outlets 16, 14 forming elbow shaped openings. FIG. 1 shows, for example, two radial openings in the section plane and two radial openings. It follows that in this example six radial grooves are present and extended with the same number of longitudinal grooves leading to the interior of the shaft.

(21) The distribution of openings 16, 14 may be uniformly spread over the periphery of the fixed collar 10.

(22) Thus the number of openings 14, 16 can be dimensioned in relation to the flowrate of the fluid to circulate in the cavity and therefore provide a degree of damping that diminishes vibration.

(23) In one embodiment, the fixed collar 10 comprises second exit openings 13, 15 disposed symmetrically in relation to the first openings 16, 14 at the other extremity of the fixed collar 10, i.e. on the external side of the shafts. Their geometry may be substantially similar to openings 14, 16, i.e. having an elbow shape. The radial openings 13 forming lumens arranged on the periphery of the fixed collar 10 are extended by longitudinal openings 15 leading to the exterior of the fixed collar 10 from the external side of shaft 30. In another embodiment, the longitudinal openings 15 form lumens traversing shoulder 17 of the fixed collar 10.

(24) The fluid 122 follows the path shown by the dotted lines in FIG. 1. The fluid 122 present in the interior of shaft 30 enters in the fixed collar 10 from the side of seal 110 and follows the elbow ducts 16, 14, then spreads throughout the circumferential cavity 18 and is then ejected via the intermediary of elbow ducts 13, 15.

(25) The circumferential cavity 18 provides the function of a vibration damper when a fluid 22, such as a lubricant, passes through it. The fluid passing through the circumferential cavity 18 permits the generation of a fluid pressure that linked to its viscosity produces an additional hydraulic damping coefficient through the absorption of energy.

(26) FIG. 2 represents a second element forming a moveable collar 20 intended to be attached to a mobile cutting tool such as machining head 50 shown in FIG. 3. The moveable collar 20 has an annular body 20A around axis 20B, and on its exterior periphery is a circumferential groove 23 adapted to receive a seal 22. The seal 22 is intended to create an area of contact between moveable collar 20 and the interior surface of the shaft to be bored or machined 30 so as to dampen part of the vibration generated while machining the shaft 30. The moveable collar 20 is arranged on the rear part of the machining head 50, i.e. on the part of head 50 the closest to junction with shaft 30. The rear part of the moveable collar 20 is the part furthest away from shaft 30 when the machining head 50 is inserted blind into shaft 30.

(27) The moveable collar 20 is fixed to machining head 50. For this purpose, it may be held in place by a locking ring 60.

(28) According to the embodiments, the moveable collar 20 may have various profiles, such as cylindrical annular profile or a chamfered profile so as to comprise a conical crown face resting on a circular and inclined face of machining head 50.

(29) The lower peripheral face 24 of moveable collar 20 rests on an upper peripheral face of the machining head 50.

(30) FIG. 3 represents an assembly with a machining head 50 comprising guide shoes 51 that are sleeved in hollow shaft 30 to bore with the aid of guide bar 40.

(31) The guide bar is 40 firmly attached to machining head 50 by way of a locking ring 60. Locking ring 60 may have a double function: to firmly attach machining head 50 to the guide bar 40; to firmly attach the moveable collar 20 to the machining head 50.

(32) Advantageously, guide bar 40 and machining head 50 comprise a means of introducing a fluid 122 such as a lubricant into shaft 30 to be machined. This lubricant may be evacuated via the fixed collar 10 as previously described. The flowrate of the injected lubricant may be adjusted according to the desired flowrate circulating in the circumferential cavity and in order to change the frequency response of the generated vibrations.

(33) The fixed collar 10 may be mounted on guide bar 40 and introduced into shaft 30 at the same time as cutting tool 50 which is linked to the guide bar 40.

(34) The fixed collar 10 and the moveable collar 20 may be made from polyamide. Furthermore, an ensemble formed by these two may be arranged before machining a shaft in such a way as to diminish the vibration generated by the machining of a long shaft. The arrangement of collar and ring may be simply carried out by selecting a fixed collar whose interior diameter is suited to the passage of a guide bar 40 and whose external diameter is suited to cooperate with the internal diameter of the shaft 30.

(35) Similarly, the moveable collar 20 can be selected so as to cooperate with a given machining head 50. It can be specifically designed for a given machining head 50. In another embodiment, the moveable collar 20 may be associated with calibration collars permitting the creation of an additional thickness between machining head 50 and moveable collar 20. This permits, for example, to produce moveable collars 20 with a greater diameter in order to be compatible with a greater number of machining heads while remaining compatible through their correct functioning.

(36) One advantage of the anti-vibration device of the invention and in particular of the fixed collar 10 is that it also has a guiding function for guide bar 40 in shaft 30. This guiding function allows greater rectilinear precision of guide bar 40 and therefore of the machining head 50 with the shaft to be bored 30.

(37) The reduction of vibration obtained with the invention is the combination of the damping effects, on one hand, produced by seals 110, 110, 121 and 22 and on the other those produced by the fluid circulating in the cavity of the fixed collar 10. The combination of these two mechanical and hydraulic damping effects permits a better control of the frequency response of the vibration generated both via mechanical retention and the viscosity coefficient.

(38) Moreover, the two damping effects permit the frequency response to be adapted to the vibration generated: on one hand, between guide bar 40 and fixed collar 10 and; on the other, between fixed collar 10 and the shaft 30 being bored, and moveable collar 20 and the shaft 30 being bored.

(39) The reduction of vibration during reaming, milling and boring of shaft 30 permits obtaining a better surface state after the said operations, and this with long shaft 30 lengths. Notably, the invention is compatible with all shaft lengths to be bored. The results and improvements in the surface state are significant with long shafts, particularly those greater than 1800 mm and going up to shafts of 2300 mm to 2500 mm in length. The invention can be applied to all diameters for reaming, milling and boring, particularly those between 30 mm and 60 mm.