Centring bush

Abstract

A centring bush (1) for the alignment and mutual coupling of two opposite substantially cylindrical cavities (H, L); the bush comprises a body (2) with cylindrical symmetry with a central axis (V), wherein the body (2) comprises a first end portion (3) with a predetermined outer diameter (D3), which can be inserted with predetermined tolerance in one of the cavities (H) to be connected, a second end portion (4) with a predetermined outer diameter (D4) which can be inserted with a predetermined tolerance into the other of the cavities (L) to be connected. The first (3) and the second end portion (4) are joined by a third annular portion (5) having a reduced outer diameter (D5) with respect to that of the first and of the second outer diameter (D3, D4). The first (3), the second (4) and the third portion (5) have the same inner diameter (Di), the reduction of outer diameter (ΔD) of the third annular portion (5) with respect to said annular end portions (3, 4) being configured to define an annular groove (7) adapted to significantly reduce the transmission of internal tensions between the end portions (3, 4) and make the radial deformations of the latter substantially independent upon insertion thereof into the respective cylindrical cavities (H, L).

Description

CENTRING BUSHDESCRIPTIONField of the invention

[0001] The present invention generally relates to the technical field of mechanical connections, and it particularly relates to a centring bush for the alignment and coupling of two members to be connected.Background art

[0002] In the field of mechanical machining operations carried out with machine tools, the need for stably fixing the unprocessed workpieces or semi-finished products to a support, for example a workpiece holder board, has been long known.

[0003] Typically, the fixing is carried out using threaded connection members designed to be screwed into a temporary hole obtained in the workpiece to be processed and constrained to a support in turn bracketed on the workpiece holder board.

[0004] Usually, the support consists of modules or columns which may have pre-established heights or which can be mutually coupled by means of a centring bush which is used to align and couple two opposite cavities without clearance.

[0005] The current alignment and connection systems between faced cavities of cylindrical type are configured so that the bush is coupled by interference between the connection member and the opposite cavities.

[0006] This condition rules out the possibility of manually fitting the bush and makes the repeated removal of the bracketing systems, for example in the event of processing operations with repeated machining operations and / or repeating the processing operations on the same machine tool, complex and strenuous.

[0007] Another alignment and connection system consists of elastic pins, see for example document CN110039334, which however do not offer the required alignment precision.Technical problem

[0008] In the light of the prior art, the technical problem addressed by the present invention is to provide a centring bush which allows to obtain an easy alignment and an easy connection without clearance between two opposite substantially cylindrical cavities.Summary of the invention

[0009] A general object of the present invention is to solve the aforementioned problem by providing a centring bush for the alignment and mutual coupling without clearance of two opposite substantially cylindrical cavities which is highly efficient and cost-effective.

[0010] A particular object is to provide a bush of the type indicated above which allows the manual insertion and removal thereof, that also is without the need for extractors and without reducing the mutual sealing of the opposite cavities.

[0011] Another particular object is to facilitate the handling of the bush thanks to a relatively complex geometry.

[0012] The objects mentioned above and others which will be more apparent hereinafter, are achieved by a centring bush for the alignment and mutual coupling of two opposite substantially cylindrical cavities, according to claim 1 .

[0013] The bush comprises a body with cylindrical symmetry with a central axis, the body comprising a first annular end portion having a first outer diameter which can be inserted with a predetermined tolerance into one of the cavities to be connected, a second annular end portion having a second outer diameter which can be inserted with a predetermined tolerance into the other of the cavities, wherein said first and said second end portion are axially offset and joined by a third annular connection portion having an outer diameter smaller than that of said first and said second outer diameter, the reduction of the outer diameter of said third annular portion with respect to said annular end portions being configured to define an annular groove adapted to significantly reduce the transmission of internal tensions between said annular end portions andmake the radial deformations of said end portions substantially independent upon insertion thereof into the respective cylindrical cavities.

[0014] Thanks to this configuration, the centring bush allows an easy alignment and an easy connection without clearance between two opposite cavities.

[0015] In an embodiment, each of said annular end portions has a configuration with three or more lobes that are angularly offset with respect to each other, even by different angles.

[0016] In an embodiment, the three-lobed configuration of the first annular portion is angularly offset by 60° with respect to the three-lobed configuration of the second annular portion.

[0017] In an embodiment, the first, the second and the third annular portion are coaxial and have the same inner diameter.

[0018] In a second aspect of the invention, there is provided a method for the alignment and mutual coupling of two opposite substantially cylindrical cavities belonging to two respective members to be connected.Brief description of the drawings

[0019] Further characteristics and advantages of the invention will be more apparent in the light of the detailed description of some embodiments of a centring bush according to the invention, shown by way of non-limiting example with reference to the drawings below, wherein:Brief description of the drawingsFIG. 1 is an overall perspective view of a centring bush according to the invention;FIG. 2 is a top view of the bush of FIG. 1 ;FIG. 3 is a top view similar to FIG. 2 which shows some characteristics of the bush of FIG. 1 ;FIG. 4 is a top view similar to FIG. 2 which shows other characteristics of the bush of FIG. 1 ;FIG. 5 is a lateral view of the bush of FIG. 1;FIG. 6 is a lateral view similar to FIG. 5 but rotated by 90° around the central axis thereof;FIG. 7 is a cross-sectional view of the bush of FIG. 4 sectioned according to diametrical plane of line VII-VII;FIG. 8 is a cross-sectional view of the bush of FIG. 4 sectioned according to diametrical plane of line VI I l-VII I;FIG. 9 is a perspective view of the bush of FIG. 1 aligned with two cylindrical cavities to be coupled;FIG. 10 is a perspective view of the bush of FIG. 1 aligned and connected to two cylindrical cavities to be coupled;FIG. 11 is a perspective view of the bush of FIG. 1 when applying radial forces;FIG. 12 is a perspective view of the bush of FIG. 1 after applying radial forces;FIG. 13 is a top view of the bush of FIG. 1 when applying radial forces to one of the end portions;FIG. 14 is a top view of the bush of FIG. 1 when applying radial forces to the other of the end portions.Detailed description of some embodiments

[0020] With reference to the mentioned figures, there is shown a centring bush, indicated in its entirety with reference numeral 1 , for the alignment and mutual coupling of two opposite substantially cylindrical cavities, respectively indicated with H and L, in particular see FIGS. 9 and 10.

[0021] By way of example, the cavities H and L may belong to two superimposed bracketing modules, or they may respectively belong to a bracketing module and to a workpiece being processed. However, it should be clear that these embodiments are not deemed exclusive and limiting and they may instead be extended to any opposite pair of cavities, whether passes through or blind.

[0022] The bush 1 comprises a body 2 with cylindrical symmetry with a central axis V, the body having a first annular end portion 3 having a first outer diameter Ds and a second annular end portion 4 having a second outer diameter D4.

[0023] The first end portion 3 can be inserted with a predetermined tolerance into the cavity H, the second end portion 4 can also be inserted with a predetermined tolerance into the second cavity L.

[0024] The predetermined tolerance may vary by a few hundredths, so as to allow a coupling that is free and precise but without clearance.

[0025] Suitably, the first end portion 3 and the second end portion 4 are coaxial and have a predetermined thickness r with appropriate value so as to allow an appropriate insertion into the cylindrical cavities H and L.

[0026] The first end portion 3 and the second end portion 4 are axially offset by a distance s and they are joined by a third annular connection portion 5.

[0027] A distinctive characteristic of the invention lies in the fact that the third connection portion 5 has an outer diameter Ds smaller than the diameter D3 of the first portion 3 and then the diameter D4 of the second end portion 4. Furthermore, all the three annular portions have the same inner diameter Di.

[0028] The difference of diameter between the third annular portion 5 and the two annular end portions 3 and 4 provides an annular groove 6, which results in difference of thickness that is such to interrupt or at least significantly reduce the transmission of internal tensions between the two annular end portions 3 and 4 upon insertion thereof into the respective cavities H and L.

[0029] Another distinctive characteristic of the invention lies in the fact that the first annular end portion 3 has a lobed configuration, in particular at least three lobes, defined by a base ring 7 with substantially constant radial thickness from which at least three lobes 8 extend, which are angularly offset by equal or different angles.

[0030] Although there has not been shown a different embodiment, the number of lobes n could be greater than three, for example four, five or six lobes without departing from the scope of protection of the invention. Therefore, generally, the lobes n will be mutually angularly offset by an angle a. Should the lobes be angularly equidistant, the offset angle a is equal to 3607n.

[0031] With reference to the three-lobed configuration, the lobes 8 have a substantially cylindrical outer surface with identical angular width y which may vary depending on the number of lobes n, for example, between 5° and 20°, so as to obtain an appropriate contact surface with a cylindrical cavity into which the end portion 3 will be inserted.

[0032] Suitably, the three lobes 8 are connected to the base ring 7 by means of suitable curvature radii so as to avoid concentrations of tensions.

[0033] The lobed configuration, in particular with at least three lobes defined for the first end portion 3 also fully applies for the second end portion 4, which is formed by a base ring 9 with a substantially constant radial thickness from which identical lobes 10 extend, angularly offset with respect to each other of the angle a equal to 3607n, which, in the case of the three-lobed configuration, it will be equal to 120°.

[0034] In an embodiment, the n-lobed-configuration of the first annular portion 3 is angularly offset by a relative angle p with respect to the n- lobed-configuration of the second annular portion 4. Generally, the relative offset angle p may be equal to 36072n.

[0035] In the case of three-lobed configuration, the three lobes 8 of the first annular end portion 3 are stacked with the three lobes 10 of the second end portion 4 but they are angularly offset by an angle p of 60° with respect to the first.

[0036] The three-lobed configuration mentioned above of the two end portions 3, 4, combined with the offset of the two three-lobed portions and with the groove 6 between the two of the two end portions is used toconcentrate the radial forces directed towards the axis V generated by the contact with the inner surface of each respective cylindrical cavity H, L on the lobes 8, 10 of each annular end portion 3, 4 angularly offset by 120°.

[0037] Obviously, should the number of lobes n be greater than three, the angular offset a between the lobes and the p one between the series of lobes of the two end portions shall correspondingly change inversely proportionally to the number of lobes n.

[0038] In all cases, the arrangement is such that the base ring 7, 9 of each end portion 3, 4 may elastically deform so that the outer surface of the lobes 8, 10 maintains a contact that is stable and without clearance with the opposite cylindrical cavities H, L.

[0039] FIG. 11 is a perspective view of the bush 1 which shows how the radial forces R generated by the insertion of the first portion 3 act in the cylindrical cavity H.

[0040] FIG. 12 shows the deformation of the first end portion 3 due to the radial forces R, which basically do not affect the configuration of the second end portion 4 in any manner whatsoever due to the interruption created by the third intermediate portion 5.

[0041] FIG. 13 shows in plan view the deformation of the second end portion 4 due to the radial forces R acting on the lobes 10, that do not cause any deformation of the first end portion 3.

[0042] FIG. 14 shows in plan view the deformation of the first end portion 3 due to the radial forces R that do not cause any deformation of the second end portion 4.

[0043] In an embodiment, the inner surface 11 of the body 2 is provided with a continuous internal thread 12 so as to allow the screwing of a threaded extractor, not shown in figure given that it is within the reach of the person skilled in the art.

[0044] In a variant embodiment, the body 2 has a smooth inner surface 11 so as to allow the insertion of a substantially cylindrical extractor andnot threaded, also not shown in figure given that it is within the reach of the person skilled in the art.

[0045] In the light of the above, it is clear that the centring bush achieves the pre-established objects, and in particular it allows the insertion thereof without clearance extremely easily, manually and without using any tool.

[0046] Although the bush has been described with particular reference to the attached figures, the reference numerals used in the description and in the claims are meant for improving the intelligibility of the invention and thus do not limit the claimed scope of protection in any manner whatsoever.

[0047] Throughout the description, reference to “an embodiment” or “the embodiment” or “some embodiments” indicate that a particular characteristic, structure or element described is comprised in at least one embodiment of the object of the present invention. Industrial applicability

[0048] The present invention is applicable at industrial level because it can be manufactured on industrial scale by industries belonging to the field of mechanical machining operations with machine tools.

Claims

CLAIMS1. A centring bush (1) for aligning and mutually coupling two opposite substantially cylindrical cavities (H, L), which bush comprises a body (2) of cylindrical symmetry with a central axis (V), wherein said body (2) comprises:- a first end portion (3) with a predetermined outer diameter (Ds) insertable with a predetermined tolerance into one (H) of the cavities to be connected;- a second end portion (4) with a predetermined outer diameter (D4), insertable with a predetermined tolerance into the other (L) of the cavities to be connected; wherein said first (3) and said second end portion (4) are joined by a third annular connection portion (5) having an outer diameter (Ds) reduced with respect to that of said first and said second outer diameter (Ds, D4); wherein said first (3), said second (4) and said third portion (5) have the same inner diameter (Di), the reduction of outer diameter (AD) of said third annular portion (5) with respect to said annular end portions (3, 4) being configured to define an annular groove (6) adapted to significantly reduce the transmission of internal tensions between said end portions (3, 4) and make the radial deformations of the latter substantially independent upon insertion thereof into the respective cylindrical cavities (H, L).

2. Bush as claimed in claim 1 , wherein each of said first and second annular end portion (3, 4) has a lobed configuration comprising a base ring (7, 9) of substantially constant radial thickness from which extend radially a predetermined number of lobes (n), at least equal to three, which are mutually angularly offset by an angle (a) and each having a pre-established angular width (y).

3. Bush as claimed in claims 2 to 4, wherein the lobes (8) of the first end portion (3) are angularly offset by a relative angle (P) with respect to the lobes (9) of the second end portion (4).

4. Bush as claimed in claims 2 and 3, wherein, the mutual offset angle (a) is equal to 120° and the relative offset angle (P) is equal to 60° in case of a three-lobed configuration.

5. Bush as claimed in claim 1 , wherein said first (3), said second (4) and said third annular portion (5) are coaxial and axially offset.

6. Bush as claimed in claim 1 , wherein the inner surface of said body (2) has an inner surface (11) provided with a continuous thread (12) for a possible screwing of a threaded extractor.

7. Bush as claimed in claim 1 , wherein the inner surface of said body (2) has a smooth inner surface (11) for the possible insertion of a substantially cylindrical extractor.

8. A method for aligning and mutually coupling two opposite substantially cylindrical cavities (H, L) belonging to two respective members to be connected, the method comprising the following steps:- providing a centring bush (1) as claimed in one or more of the preceding claims;- manually inserting the first end portion (3) of the bush into the cavity (H) of the first member thereby allowing the deformation of said first end portion (3);- inserting the second end portion (4) of the bush into the cavity (L) of the second member thereby allowing the deformation of said second end portion (4); wherein due to the effect of the annular groove (6) defined by the reduction of the outer diameter (Ds) of said third annular portion (5) with respect to said first (3) and said second end portion (4), the deformations of said end portions (3, 4) are substantially independent of each other in order to facilitate the manual insertion of the bush (1) into the respective cavities (H, L).

9. Method as claimed in claim 8, wherein the removal of said first and second annular end portion (3, 4) from the respective cavities (H, L) is carried out with the aid of a rod-shaped extractor having a threaded end which can be screwed into the internal thread (12) of the body (2) of the bush.

10. Method as claimed in claim 8, wherein the removal of said first and second end portion (3, 4) from the respective cavities (H, L) is carried out with the aid of a rod-shaped extractor having a substantially cylindrical end which can be inserted into the smooth inner surface (11) of the body (2) of the bush (1).

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