Tool for mounting and removing tyres onto and from respective wheel rims

Abstract: Tool for mounting and removing tyres onto and from respective wheel rims comprises a profiled body to be mounted on a cylindrical shank (2) provided at the end of a tool holder bar (1) associated with a tyre removal machine, the body having two active portions, known as the blade (5) and head (6) respectively, extending from two parts (20, 22) comprising coaxial hubs (200, 220) both mounted on said cylindrical shank (2) of said tool holder bar and removably coupled together such that their mutual orientation can be adjusted, at least one of said hubs (200, 220) being provided with means for torsionally locking it to said shank.

Description: This invention relates to a tool for inserting and extracting tyre beads into and from their retention seats of respective wheel rims while fully respecting the integrity of said beads whatever the nominal diameter of said wheel rims. Modern tyre removal machines, typically for automobile and other light vehicle wheels and for motorcycle wheels, are known to comprise, inter alia, a usually horizontal self-centering unit provided for locking the wheel rims, and an overlying tool for mounting and removing the respective tyres, this acting between the bead retention edge of the wheel rim and the tyre bead. Said tool can be adjusted both vertically and horizontally, in order to adapt its operating position to wheel rims of different widths and diameters. In particular, said tool is supported by a vertical bar slidable in height and supported by a horizontal arm which is slidingly mounted on the top of a column situated behind the self-centering' unit. More specifically, said tool consists of an elongate profiled one-piece body to be positioned transversely to said bar, and comprising two active portions positioned on one and the other side of said bar. One of said active portions is formed in practice as a blade or tongue intended to lie virtually coplanar with the upper bead retention edge of the wheel rim locked on the self-centering unit, the other presenting a substantially hemispherical head intended to lie facing the said bead retention edge and presenting a jutting protuberance situated on the opposite side to that occupied by said blade or tongue. The purpose of said protuberance is to provide the support and turning region for the usual bead lifting levers used by tyre operators in disengaging the beads from the bead retention seats on the respective wheel rims. As stated, these known tools are in the form of a one-piece body, which has proved unsatisfactory for the following reasons. In this respect, as modern vehicle and motorcycle wheel rims can have considerably different nominal diameters, the said one-piece tool construction means that said tongue or said protuberance on said known tools often assumes an operating position relative to the wheel rim which is displaced from the optimum required for easy and correct extraction and insertion of the respective tyre' beads. With particular reference to the extraction of a bead from the respective edge of its wheel rim, said optimum position of the tool relative to the wheel rim is that in which the support protuberance for the bead lifting lever is practically parallel to the straight line tangential to that region of the bead retention edge which is close to said protuberance, the blade passing beyond said bead retention edge by a distance of the same order of magnitude as the radial dimension of the bead. Known tools can occupy an operating position close to the aforedefined optimum for only a part of the range of possible nominal wheel rim diameters, for example medium-large and large diameters, whereas their operating position deviates from the optimum even by a large extent for other diameters within the range, for example intermediate and small diameters. In particular, if the tool is not correctly positioned relative to a circle of relatively small diameter, the respective protuberance is inclined outwards from the straight line tangential to that region of the bead retention edge behind the protuberance, and the blade extends beyond the end of the bead retention edge by a distance which is relatively large compared with that for wheel rims of intermediate and relatively large nominal diameters. Said inclination of the protuberance results in a corresponding distancing of the respective support region for the bead lifting lever away from the bead retention edge of the wheel rim, this creating a problem when the bead has to be lifted onto the hemispherical head of the tool to arrange it for extraction. In this respect, seeing that said inclination of the protuberance increases the distance of its free end from the bead retention edge, and that in order to lift the bead onto the head by the bead lifting lever the bead has to pass beyond the free end of the protuberance, said bead must be deformed to a greater extent than would occur if the protuberance were correctly positioned as aforestated. In addition to requiring considerable force by the tyre operative, this can subject the bead to problems and/or excessive stress, with possible damage such as stretching, local weakening and cracking. Other possible local damage can also derive from the settling of the bead lifting lever, in particular from the oscillation to which said lever is subjected when, starting from its transverse orientation defined by the wedging of its end between the bead and the respective bead retention edge, it is pulled with force against the protuberance, which as stated is inclined to the tangent passing through that portion of the bead retention edge situated at the protuberance. Said problems assume particular importance for tubeless tyres. Moreover, at the moment the upper bead is extracted from the respective bead retention edge of a wheel rim of relatively small diameter, where as stated the blade extends beyond the end of said bead retention edge by a relatively large distance, the free edge of the blade can interfere with the sidewall of the tyre, with consequent inconvenient rubbing between the two during rotation of the self-centering unit. Consequently, with the self-centering unit in movement similar rubbing also occurs between the sidewall of the tyre and the blade during insertion of the lower bead, and between the sidewall and the free end of the protuberance during extraction of the lower bead. A tool according to the above mentioned features is known from us 5,472,034. In an attempt to overcome this problem, certain parties, including the Applicant, have proposed tools, again consisting of a one-piece body shaped as specified in the introduction, which are intended to be positioned at the end of a vertical bar such that their angular position can be adjusted. In particular, said tools comprise an intermediate tube to be mounted as an exact fit on a lower cylindrical end shank of said bar, and be locked thereat by suitable means, such as a ring nut or the like. In addition, said shank is provided with a surface flattening, and with two transverse adjacent through screws the points of which make contact with said surface flattening. To swivel the tool in one direction or the other, one of said screws has firstly to be loosened and then the other screwed tightly down. However this solution has also proved unsatisfactory at least for the following two reasons. The first is the fact that said loosening and tightening operations are relatively lengthy and complicated. The second is the fact that as the tool is in one piece, its two opposing active portions cannot be independently adjusted, with the result that when one of them is positioned correctly, the other can occupy an inconvenient position. Essentially, if the protuberance is positioned virtually parallel to the tangent passing through that part of the circle close to said protuberance, the blade can project excessively from the end of the bead retention edge, and if the blade is positioned to pass beyond said end by a distance of the same order of magnitude as the radial dimension of the bead, the protuberance can be inconveniently inclined to said tangent, with the aforegoing drawbacks. In this specific sector there is therefore a widely felt need for a tool able to overcome the aforesaid problem, without having to use two or more tyre removal machines each having a tool suitable for a specific part of the range of current nominal wheel rim diameters. The main object of the present invention is precisely to satisfy said requirement within the context of a simple, rational, economical, reliable and durable construction. Said object is attained by the characteristics indicated in the claims. In a general sense, said object is attained by providing a tool in the form of a system of variable shape, which can be adjusted as required on the basis of the nominal diameter of the wheel rim which at that moment is locked on the self-centering unit of a tyre removal machine. In particular, as will be more apparent hereinafter, it comprises two parts, of which one carries said blade and the other supports said head with its protuberance, these being provided with two coaxial annular elements or hubs which are mounted on the cylindrical end shank of the tool holder bar, and are stably coupled together such that their mutual orientation can be adjusted. At least one of said parts can be torsionally locked to the shank, with the desired orientation. By means of the aforesaid solution all the objects of the invention are attained, as will be apparent hereinafter. The constructional characteristics and merits of the invention will be apparent from the ensuing detailed description given with reference to the figures of the accompanying drawings which illustrate some particular preferred embodiments thereof by way of non-limiting example. Figure 1 is an exploded perspective view showing a first embodiment of the invention. Figure 2 is a sectional rear (with reference to its active portions) elevation showing the tool of Figure 3 in an assembled configuration. Figure 3 is a section on the line III-III of Figure 2 on a smaller scale, in which the tool is shown in the configuration suitable for operating on wheel rims having a relatively large nominal diameter. Figure 4 is a view similar to the preceding, showing the tool in the configuration suitable for wheel rims of intermediate nominal diameter. Figure 5 is a view similar to Figures 3 and 4, showing the tool in the configuration suitable for wheel rims of relatively small nominal diameter. Figure 6 is a sectional rear elevation showing a second embodiment of the invention. Figure 7 is a part of the section on the line VII-VII of Figure 6. Figure 8 is a section on the line VIII-VIII of Figure 6 showing the tool in the configuration suitable for wheel rims of relatively large nominal diameter. Figure 9 is a view similar to the preceding, showing the tool in the configuration suitable for wheel rims of relatively small nominal diameter. Figure 10 is a front elevation of a third embodiment of the invention. Figure 11 is a section on the line XI-XI of Figure 10. Figure 12 is a section on the line XII-XII of Figure 10, in which the tool is shown in the configurations suitable for relatively large diameter wheel rims and relatively small diameter wheel rims by full lines and dashed and dotted lines respectively. Figure 13 is a sectional rear elevation showing a fourth embodiment of the invention. Figure 14 is a partial view in the direction XIV of Figure 13. Figure 15 is a section on the line XV-XV of Figure 13 showing the tool in the configuration suitable for wheel rims of relatively large nominal diameter. Figure 16 is a view similar to the preceding, showing the tool in the configuration suitable for wheel rims of relatively small nominal diameter. Figure 17 is a view similar to Figure 14, showing a variant of the embodiment shown in this latter figure. Figure 18 is a section on the line XVIII-XVIII of Figure 17, showing the tool in the configuration suitable for wheel rims of relatively large nominal diameter. Figure 19 is a view similar to the preceding, showing the tool in the configuration suitable for wheel rims of relatively small nominal diameter. Figure 20 is a view similar to Figure 17, showing a further variant. Figure 21 is a section on the line XXI-XXI of Figure 17 showing the tool in the configuration suitable for wheel rims of relatively large nominal diameter. Figure 22 is a view similar to the preceding, showing the tool in the configuration suitable for wheel rims of relatively small nominal diameter. From said figures it can be seen that the tool in question is intended to be positioned on the lower end of a usual height-adjustable vertical prismatic bar 1 positioned above a likewise usual self-centering unit (not shown) of a tyre removal machine. Said bar can be adjusted in known manner not only in height, but also radially about the vertical axis (indicated by 100 in Figures 3 to 5) about which the self-centering unit rotates. At the lower end of the bar 1 there is a cylindrical shank 2 for receiving the tool of the invention as a precise fit. In all the illustrated embodiments the tool comprises two parts 20 and 22, comprising two coaxial hubs 200 and 220 to be mounted on the shank 2, on which they lie between the shoulder at the top of said shank 2 and a washer 3 which is fixed to the end of the shank 2 by a screw 4. Said two hubs 200 and 220 are not clamped tightly against each other between said shoulder and said washer 3, but instead are simply maintained in mutual contact such as to enable them to be rotated about the longitudinal axis of the bar 1 without requiring particular force. The part 20 comprises a first active portion, of usual type indicated by 5 in the figures, hereinafter known as the blade or tongue as stated in the introduction, and the part 22 is provided with a second active portion, also of usual type, comprising a hemispherical head 6 which rests on an idle conical roller 7, and carries a jutting protuberance 8. The function of said tongue 5, head 6, roller 7 and protuberance 8 is known. It is sufficient to note that on withdrawing or inserting a tyre bead these are positioned as stated in the introduction and as shown in Figures 3 to 5, which in practice are schematic plan views of a self-centering unit of vertical axis 100. According to said first embodiment, the angular positions of the two parts 20 and 22 of the tool can be adjusted relative to the shank 2 in the manner of a compass. For this purpose, from the facing circumferential edges of the hubs 200 and 220 there extend two portions in the form of a cylindrical segment of less than 180° extension, said segments being indicated by 23 and 24 respectively. Said portions 23 and 24 have the same height so that between their facing sides there are defined two gaps for receiving the control unit which will now be described. This comprises a threaded rod 25 which is screwed into a through diametrical threaded hole 250 provided in the shank 2, and passes through said gaps between said sides. On the opposite ends of said threaded rod 25 there are a first 26 and a second 27 thrust cone the minor bases of which face the shank 2, their inclined surfaces making constant contact with the vertical edges of said gaps (see Figures 3 to 5). The rod 25 presents a knurled operating knob 28 and a locking nut 29. On rotating the rod 25 in one direction or the other it undergoes a corresponding axial movement (see Figures 3 to 5) by which as one cone, such as 27, becomes increasingly inserted between the respective facing sides of the portions 23 and 24, the opposing thrust cone, such as 26, withdraws from the opposite facing sides. Simultaneously the two parts 20 and 22 of the tool rotate in one direction or the other about the shank 2 through the same angle but in opposite directions. By this means, the tyre operative can adapt the shape of the tool to the nominal diameter of the wheel rim onto or from which the tyre is to be mounted or removed, as shown in Figures 3 to 5. In Figure 3 the reference numerals 70 and 77 indicate a wheel rim of relatively large nominal diameter D 3 , and the respective upper bead retention edge; in Figure 4, the reference numerals 80 and 88 indicate a wheel rim of average nominal diameter D 2 , and the respective upper bead retention edge; and in Figure 5 the reference numerals 90 and 99 indicate a wheel rim of relatively small nominal diameter D 1 , and the respective upper bead retention edge. There is also provided an arched apron 21 (see Figures 1 and 3-5) which is rigid with the part 22, its purpose being to close the lateral gap 210 formed between the two parts 20 and 22 (see Figures 4 and 5) to prevent entry of foreign bodies between them. By means of said adjustment, the tool blade 5 and protuberance 8 can be disposed in the most convenient position for extracting or inserting a bead, and in particular the protuberance 8 can be disposed practically tangential to the bead retention edge 77 or 88 or 99, and the outer free edge of the blade 5 can be positioned such that it passes beyond the end of said bead retention edge 77 or 88 or 99 by' a distance of the same order of magnitude as the radial dimension of the bead. According to the second embodiment shown in Figures 6 to 9, the angular position of the tool parts 20 and 22 is adjusted by the following means. These comprise a spindle 30 which is rotatably mounted in a through diametrical hole provided in the shank 2, and presents a knurled end knob 280 for its operation. The spindle 30 carries two identical elliptical plugs 31 and 32 which are offset by 90° and are received within the gaps defined by the pairs of facing sides of the already described portions 23 and 24. The facing faces of said two plugs 31 and 32 are spaced apart by a distance practically equal to the diameter of the shank 2, so that the spindle 30 is locked in the axial direction. Rotation of the spindle 30 in one direction or the other results in simultaneous rotation in opposite directions of the two tool parts 20 and 22, which can assume any position between the two shown in Figures 8 and 9, which correspond to those shown in Figures 3 and 5 respectively. According to the third embodiment shown in Figures 10, 11 and 12, the two tool parts 20 and 22 can be adjusted relative to each other and to the bar 1 independently. As shown in Figure 11, the washer 3, fixed by the screw 4, is provided at the lower end of the shank 2. The hubs 200 and 220 of the tool parts 20 and 22 are mounted on the shank 2. In this version the portions 23 and 24 are missing, whereas the lower edge of the bar 1, both edges of the hub 200 and the upper edge of the hub 220 are provided with matching teeth indicated by 661 and 662 respectively. To adjust the angular position of one or both the tool parts 20 and 22 the screw 4 is slackened by a sufficient amount, then one or other or both the tool parts 20 and 22 are rotated by the desired amount, and finally the screw is again tightened. In Figure 12 the tool is shown in its configuration for wheel rims of relatively large nominal diameter and in its configuration for wheel rims of relatively small nominal diameter by continuous lines and by dashed and dotted lines respectively. According to the fourth embodiment shown in Figures 13 to 16, and according to a first (Figures 17 to 19) and a second (Figures 20 to 22) variant of said fourth embodiment, the tool parts 20 and 22 are mounted idle on the shank 2 by the respective hubs 200 and 220. Along the mutually contacting edges of said hubs 120 and 220 there are provided two recesses 50 located on one and the other side of a milled slot 52 provided in the shank 2. In Figures 13 to 16 the means for adjusting the tool parts 20 and 22 comprise two holed lugs 54 which are fixed to one hub 200 and to the other 220 at said recesses 50, and each carrying an idle ball 56 with a threaded through hole. The threads of said holes are opposite-handed, with said threads there engaging the opposite-handed threads of a threaded rod 58 positioned tangential to the hubs 200 and 220. Said threaded rod 58 is also provided with a central knurled operating wheel 580 the rear portion of which is partly inserted into said slot 52. In the variant of Figures 17 to 19, the opposite-handed threaded ends of said rod 58 are engaged with the threads of two threaded diametrical through holes provided in the central part of two cylinders 62. The cylinders 62 are mounted idle within respective sleeves 64 fixed parallel to the hubs 200 and 220, which are disposed on one and the other side of said milled slot 52 parallel to the hubs 200 and 220, to straddle the horizontal plane of contact of the hubs, and present suitable lateral slots 680 to enable the threaded rod 58 to rotate. Finally, in the variant of Figures 20 to 22, two sleeves 640 situated on one side and the other of the hub plane of contact are fixed to the hubs 200 and 220. With each sleeve 640 there is associated a cylinder 620 having two portions of different outer diameter (Figure 22), of which that of lesser diameter is contained within the respective sleeve 640 and retained there by an end screw 621, and the other presents a through diametrical threaded hole with which there engages the respective end part of the control screw 58. The operation of the aforedescribed fourth embodiment and of its two two variants is apparent from that shown in the respective figures and from that heretofore described. The merits and advantages of the invention are clear from the aforegoing and from an examination of the figures.

Claims: A tool for mounting and removing tyres onto and from respective wheel rims, comprising a profiled body to be mounted on a cylindrical shank (2) provided at the end of a tool holder bar (1) associated with a tyre removal machine, the body having two active portions, known as the blade (5) and head (6) respectively, characterised in that said blade and said head extend from two parts (20, 22) comprising coaxial hubs (200, 220) both mounted on said cylindrical shank (2) of said tool holder bar and removably coupled together such that their mutual orientation can be adjusted, at least one of said hubs (200, 220) being provided with means for torsionally locking it to said shank. A tool as claimed in claim 1, characterised in that each of said hubs (200, 220) comprises a first circular cylindrical portion from which there rises a second portion (23, 24) consisting of a cylindrical segment extending through less than 180°, one of said hubs being associated, when in an inverted' position, with the other hub such that the respective second portions mutually copenetrate to allow the two hubs the ability to mutually rotate, between said two hubs there being provided means for torsionally locking them together. A tool as claimed in claim 2, characterised in that said means for torsionally locking the two hubs (200 and 220) together comprise a threaded rod (25) provided with an end operating knob (28) and screwed into a threaded diametrical hole provided through the cylindrical shank (2) on which the hubs are mounted, and carrying fixed thereon two identical cones (26, 27) the vertices of which are orientated towards said shank and the outer surfaces of which contact the sides of said second portions (23, 24) of the hubs. A tool as claimed in claim 2, characterised in that said means for torsionally locking together the two hubs (200 and 220) comprise a spindle (30) provided with an end operating knob (280) and rotatably mounted, but axially locked, in a diametrical hole provided through the cylindrical shank (2) on which the hubs are mounted, and presenting two identical plugs (31 and 32) offset by 90° which are inserted as an exact fit between the sides of said second portions (23 and 24) of the hubs. A tool as claimed in claim 2, characterised in that said means for torsionally locking together the two hubs (200 and 220) comprise a pair of matching frontal toothings (661) provided along the mutually facing edges of said hubs. A tool as claimed in claim 5, characterised in that a second pair of matching frontal toothings (662) is provided between the upper hub (200) and the base of the cylindrical shank (2). A tool as claimed in claim 2, characterised in that said means for torsionally locking together the two hubs (200 and 220) comprise a rotatable threaded control rod (58) which is axially immovable relative to the shank (2), and presents two threaded portions with opposite-handed threads engaged in two lugs (54) branching from the hubs. A tool as claimed in claim 7, characterised in that said threaded rod (58) is made axially immovable by a knurled central operating wheel (580), of which that portion facing the shank is inserted between the sides of said second portions (23, 24) of the hubs, and is contained in a slot (52) in said shank. A tool as claimed in claim 7, characterised in that articulation devices in the form of a ball joint (56) are provided between the threaded portions of the rod (58) and the lugs (54). A tool as claimed in claim 9, characterised in that said articulation devices each consist of a cylindrical joint (62, 620). A tyre removal machine, characterised by being equipped with a tool in accordance with claims 1 to 10.

Inventors: VIGNOLI GIULIANO, VIGNOLI, GIULIANO
Applicants: SICESP ELETTROMECCANICHE, SOCIETA' ITALIANA COSTRUZIONI ELETTROMECCANICHE - S.I.C.E. - S.P.A.
Application year: 2001
Main classification: B60C25
IPC codes: B60C25