TECHNICAL FIELD

[0001] The present invention relates to an apparatus for buffing railway vehicle axles.

BACKGROUND ART

[0002] Rail car axles are subjected to heavy loads, which will affect their fatigue resistance. Axle fatigue cracks may be undetectable during routine safety inspections. It can be necessary to buffer axles to enable fatigue crack identification. This is conventionally performed manually in a Computer Numerical Control (CNC) lathe. Such manual operation can be exceedingly dangerous.

[0003] The preceding discussion of the background to the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia or any other country as at the priority date.

SUMMARY OF INVENTION

[0004] In accordance with the present invention, there is provided an axle buffer for buffing vehicle axles, the axle buffer comprising a buffer, a buffer rotating means and a buffer locating means, wherein the buffer locating means comprises means to radially move the buffer relative to the axle surface and to provide a substantially constant pressure to the axle surface during operation.

[0005] In the context of the present specification, the term radially shall be understood to reference to the radius of the axle.

[0006] The means to radially move the buffer relative to the axle surface may be provided in the form of a ram. Preferably, there is provided a corresponding housing for the ram. As is known in the art, rams are operable in a retracted state and an extended state as well as transitioning between the two states. In the retracted state, the majority or all of the ram is retained inside the housing. In the extended state, the majority or all of the ram is outside of the housing. [0007] The ram may be a pneumatic ram.

[0008] Actuation of the ram may be controlled by at least one valve in engagement with the pneumatic fluid.

[0009] The valve may be provided in the form of a solenoid activated control valve. In one form of the invention, the solenoid is an NC solenoid.

[0010] Preferably, there are provided two solenoids. The solenoids may be located between the source of pneumatic fluid and the ram.

[0011] Activation of a solenoid causes fluid flow to the ram, resulting in ram actuation. In the context of the present specification, the term ram actuation shall be understood to result in the ram moving from its retracted position to its extended position.

[0012] Solenoids may be configured to deliver fluid to rams at set pressures. Where there are provided two solenoids, they are preferably configured to deliver fluid to the ram at different pressures to each other. In the context of the present specification, the solenoid that delivers fluid at the higher pressure is termed the high pressure solenoid and the solenoid that delivers fluid at the lower pressure is termed the low pressure solenoid.

[0013] Where there are provided two solenoids, there is preferably a high pressure solenoid and a low pressure solenoid.

[0014] Preferably, the high pressure solenoid delivers fluid to the ram at a pressure of between 10 psi and 50 psi. More preferably, the high pressure solenoid delivers fluid to the ram at a pressure of between 10 psi and 30 psi. In one form of the invention, the high pressure solenoid delivers fluid to the ram at a pressure of about 20 psi.

[0015] Preferably, the low pressure solenoid delivers fluid to the ram at a pressure of between 1 psi and 10 psi. More preferably, the high pressure solenoid delivers fluid to the ram at a pressure of between 3 psi and 5 psi. In one form of the invention, the high pressure solenoid delivers fluid to the ram at a pressure of about 4 psi.

[0016] It will be appreciated that the solenoid or solenoids must be capable to converting input pressure into the desired output pressure. [0017] Actuation of the high pressure solenoid actuates the ram and drives the buffer towards the operating face of the axle, ensuring that the ram is fully extended prior to probing operation.

[0018] Actuation of the low pressure solenoid applies a substantially constant pressure onto the axle face during buffing operation.

[0019] Operating the buffer under the actuation of the low pressure solenoid enables the buffer to allow for differential abrasion on the axle surface and allow for differences in axle diameter along the axle surface, such as the diameters for the axle journal, wheel seat and radius. The buffer is adapted to apply substantially constant pressure to the axle radius irrespective of the diameter. The application of the low pressure solenoid enables the buffer to account for imperfections in the axle surface and for example, to axle surface radial grooves. As the pressure of the low pressure increases, a greater pressure is applied to the axle surface by the buffer. This can create excessive wearing of the buffer wheel.

[0020] The axle buffer is preferably provided with a proximity sensor to sense the axle surface. The proximity sensor provides a limitation for the ram and also provides an electronic indication I reference for the CNC operation. This reference gives a starting point for the X axis on the lathe to return to when starting buffing operation.

[0021] The axle buffer is preferably provided with drive means for rotatably driving the buffer. Said drive means may be provided in the form of an air driven or electrically driven motor. Actuation of the drive means causes rotation of the buffer.

[0022] The drive means is rotatably connected to the buffer. In one form of the invention, the drive means is rotatably connected to the buffer by way of a timing belt. The timing belt may comprise two timing pulleys. The first timing pully indirectly or directly engages the drive means. Preferably, the first timing pully directly engages the drive means via a rotatable shaft on the drive means.

[0023] The second timing pully indirectly or directly engages the drive means. Preferably, the second timing pully indirectly engages the drive means. In one form of the invention, a buffer spindle directly engages the second timing pulley. The buffer spindle may also directly engage the buffer. [0024] The rotatable shaft may be eccentrically mounted in a housing boss.

[0025] The axle buffer may be provided with means to attach it to a CNC lathe.

[0026] In accordance with the present invention, there is provided a method for buffing a vehicle axle with an axle buffer, the method comprising the steps of: extending a ram under a first pressure from a corresponding ram sleeve on the axle buffer to an extended orientation; maintaining the ram in the extended orientation; moving the axle buffer towards the axle surface such that a buffer wheel on the axle buffer engages the axle surface under pressure, whereby a portion of the ram retracts into a ram housing, thereby establishing a probing position; moving the axle buffer away from the axle surface such that the buffer wheel disengages the axle surface; rotating the buffer wheel; moving the axle buffer back to the probing position; applying a second pressure to the ram; such that the buffer wheel engages the axle surface under said second pressure and buffs the axle surface.

[0027] In one form of the invention, the step of extending a ram from a corresponding ram housing on the axle buffer to an extended orientation comprises activating a valve on the axle buffer.

[0028] Where the method of the invention comprises the step of activating a valve on the axle buffer, the method comprises the additional step of deactivating the valve once the ram is in the extended orientation.

[0029] The valve may be provided in the form of a solenoid activated control valve. [0030] In one form of the invention, the step of applying a second pressure to the ram comprises activating a second valve. The second valve may be provided in the form of a second solenoid activated control valve.

[0031] The ram may be a pneumatic ram.

[0032] The first solenoid and the second solenoid may deliver fluid to the ram at different pressures to each other. In the context of the present specification, the solenoid that delivers fluid at the higher pressure is termed the high pressure solenoid and the solenoid that delivers fluid at the higher pressure is termed the low pressure solenoid.

[0033] Where there are provided two solenoids, there is preferably a high pressure solenoid and a low pressure solenoid.

[0034] Preferably, the high pressure solenoid delivers fluid to the ram at a pressure of between 10 psi and 50 psi. More preferably, the high pressure solenoid delivers fluid to the ram at a pressure of between 10 psi and 50 psi. In one form of the invention, the high pressure solenoid delivers fluid to the ram at a pressure of about 20 psi.

[0035] Preferably, the low pressure solenoid delivers fluid to the ram at a pressure of between 1 psi and 10 psi. More preferably, the high pressure solenoid delivers fluid to the ram at a pressure of between 3 psi and 5 psi. In one form of the invention, the high pressure solenoid delivers fluid to the ram at a pressure of about 4 psi.

[0036] The step of extending a ram under a first pressure from a corresponding ram housing on the axle buffer to an extended orientation preferably comprises activating the high pressure solenoid.

[0037] Actuation of the high pressure solenoid valve actuates the ram and drives the buffer towards the operating face of the axle, ensuring that the ram is fully extended prior to probing operation. It will be appreciated that if the pressure is too high then the ram may not retreat or may require excessive force to retreat during the establishment of the probing position.

[0038] Actuation of the low pressure solenoid applies a substantially constant pressure onto the axle face during buffing operation. [0039] Operating the buffer wheel under the actuation of the low pressure solenoid enables the buffer wheel to allow for differential abrasion on the axle surface and allow for differences in axle diameter along the axle surface, such as the diameters for the axle journal, wheel seat and radius. The axle buffer is adapted to apply substantially constant pressure to the axle radius irrespective of the diameter. The application of the low pressure solenoid enables the buffer wheel to account for imperfections in the axle surface and for example, to axle surface radial grooves. As the pressure of the low pressure increases, a greater pressure is applied to the axle surface by the buffer wheel. This can create excessive wearing of the buffer wheel.

[0040] In one form of the invention, the step of moving the axle buffer towards the axle surface such that a buffer wheel on the axle buffer engages the axle surface under pressure, such that a portion of the ram retracts into the ram housing, thereby establishing a probing position; is monitored by a proximity sensor.

[0041] In one form of the invention, retraction of the ram into the housing is monitored by a proximity sensor. The proximity sensor provides a limitation for the ram and also provides an electronic indication I reference for the CNC operation.

[0042] In one form of the invention, the step of rotating the buffer wheel; comprises operation of a drive means such as an air driven or an electrically driven motor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Further features of the present invention are more fully described in the following description of a non-limiting embodiment thereof. This description is included solely for the purposes of exemplifying the present invention. It should not be understood as a restriction on the broad summary, disclosure or description of the invention as set out above. The description will be made with reference to the accompanying drawings in which: Figure 1 is an isometric view of an axle buffer in accordance with an embodiment of the present invention;

Figure 2 is an exploded isometric view of an axle buffer in accordance with an embodiment of the present invention; and

Figure 3 is an isometric view of a portion of an axle buffer in accordance with an embodiment of the present invention; and

Figure 4 is a side view of an axle buffer in accordance with an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

[0044] Throughout the specification, unless the context requires otherwise, the word "solution" or variations such as "solutions", will be understood to encompass slurries, suspensions and other mixtures containing undissolved solids.

[0045] Throughout this specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[0046] Those skilled in the art will appreciate that the invention described herein is amenable to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps, features, compositions and compounds referred to or indicated in the specification, individually or collectively and any and all combinations or any two or more steps or features.

[0047] Figure 1 provides an isometric view of an embodiment of the axle buffer 10 of the present invention. Figure 2 provides an exploded isometric view of an embodiment of the axle buffer of the present invention. The axle buffer 10 comprises a spigot 12 for attachment to the tool turret of a CNC machine (not shown). The axle buffer is driven by an air motor 14. The air motor 14 is housed in a housing boss 16. A spindle 18 at a first end of the air motor 14 engages a first timing pulley 20 that in turn drives the buffer that engages the axle (not shown) i.e. the rotatable movement of the buffer is controlled by the air motor 14. In the present embodiment, the air motor 14 is a 2 hp pneumatic motor that spins at 3500 rpm.

[0048] A bracket 30 is provided between the housing boss 16 and the first timing pulley 20. A second timing pulley 32 rotationally engages with the first timing pully 20 via a timing belt 34. The timing belt 34, the first timing pully 20 and the second timing pulley 32 are housed within a belt guard 36. The bracket 30 is retained within the belt guard by two bolts 38.

[0049] The bracket 30 is provided with four elongate slots 50 to retain the bolts 52 that engage the housing boss 16. The elongate slots 50 facilitate adjustment of the bracket.

[0050] The air motor 14 is housed eccentric within the housing boss 16. To tension the belt 34, the boss 16 is rotated and the four bolts 52 tightened to retain the belt 34 in the tensioned position. This provides a mechanism to tighten the belt 34 without taking the axle buffer 10 apart and effectively reduces the number of parts that would be required to tension the belt and condenses the overall assembly.

[0051] The second timing pulley 32 is engaged by a first end 60 of a buffer spindle 62. A buffer flange 64 engages the second end 65 of the buffer spindle 62. The buffer flange 64 comprises an annular ridge 66.

[0052] A ball bearing set 68 is slid onto the buffer spindle 62 until it abuts a shoulder 67 on the buffer spindle 62. A circlip 70 abuts the ball bearing set 68. A double ended seal 72 is slid onto the annular ridge 66 of the buffer flange 64 and fits within the buffer spindle hub 74. The buffer flange 64 is slid onto the buffer spindle 62 and the double ended seal compacted. The buffer spindle 62 passes through the buffer spindle hub 74 The first end 60 of the buffer spindle 62 passes through the smaller aperture 76 in the bracket 30, through the aperture in the second timing pulley 32 and is retained by belt guard 36.

[0053] The buffer spindle hub 74 comprises an annular shoulder 80. A ball bearing set 82 and a circlip 84 sit inside the annular shoulder 80. The ball bearing set 82 abuts a shoulder 86 on the buffer spindle 62. [0054] Figure 3 shows an alternate view of axle buffer 10 depicting the attachment of the spigot 12 to the CNC turret 90 and the abrasive buffer 92. The buffer flange 64 is not visible and is behind the abrasive buffer 92. The abrasive buffer 92 is held in place on the buffer spindle 62 by a second buffer flange 94 indirectly engaging with the first buffer flange 64. The second buffer flange 94 is retained by a bolt 96 on the second end 65 of the buffer spindle 26. Bracing of the first buffer flange 64 and the second buffer flange 94 inhibits the abrasive buffer 92 from rotating on the buffer spindle 62.

[0055] The buffer spindle hub 68 is held by a two piece clamp 100. The first piece 102 and the second piece 104 of the two piece clamp are held together by bolts 106. The two piece clamp enables simple removal of the axle buffer from the CNC machine for maintenance.

[0056] The first piece 102 of the two piece clamp 100 is attached to a ram 110. Actuation of the ram 110 results in an extension movement of the buffer 92 relative to the axle radius. Actuation of the ram 110 is by way of a series of solenoids of different pressure. The differential pressures result in different degrees of movement of the buffer.

[0057] The ram 110 is adapted to move up and down inside a housing 112. A shoulder bolt 114 is shown adjacent an orifice 116 on the ram 110. In use, the shoulder bolt 114 enters the housing via an elongate slot 118 in the housing 112 and then proceeds into the orifice 116. The shoulder bolt stops the ram 110 disengaging from the housing 112 under pressure and limits the ram 110 to one dimensional movement only. A dust cover 120 secured with bolts 122 protects the internal workings of the ram 110 and the housing from dust and foreign body ingress 112.

[0058] The opposed end of the housing 112 comprises the spigot 12 adapted for attachment to a CNC tool turret. The spigot 12 has a rack (not shown) that engages a corresponding pinion on the turret. Seals are provided between the housing 112 and the spigot 12. An o-ring seal 130 sits in a groove inside the housing 112 and acts to seal compressed air therein. A lip seal 132 sits on the leading face of the housing 112 and prevents the ingress of dust inside the housing 112. A retaining flange 134 is secured to the housing 112 by a series of bolts 136. A further o-ring 138 sits in an annular groove 140 in the ram 110. [0059] A flange 140 is provided to support the bracket 30. The flange 140 comprises an elongate slot 142 to retain the lower portion of the bracket 30. After assembly of the device, the annular shoulder 80 of the buffer spindle hub 74 is welded to the bracket 30 and the bracket 30 inserted into the slot 142 and welded to the flange 140. The flange 140 is welded to the buffer spindle hub 74. Securing of these components provides rigidity to withstand the rotational forces from the air motor 14.

[0060] The housing boss 16 is provided with opposing keys 150 to secure the motor 14 in the boss 16. The keys 150 are bolted into slots 152 in the boss and rest on corresponding flats 154 on the motor 14.

[0061 ] The axle buffer is provided with a proximity sensor to register feedback to the CNC computer. The sensor enables a reference of actual tool positioning and to register the buffer wheel condemning limit to prevent collision throughout the automated process.

[0062] A pneumatic connection 150 is provided for actuation of the solenoids.

[0063] The present invention was designed to reduce the need for manually buffering axles in a CNC axle lathe which exposed technicians to rotating equipment with potential for entanglement

[0064] The axle buffer of the present invention is fully programmed to follow the entire machined surface of the axle profile. This enables superior surface finish to the prior art for performing the necessary crack testing required to qualify axles for service. It also provides a superior finish for the installation of bearings and the mounting (pressing) of new wheels onto the axle.

[0065] The ram and solenoids advantageously allow for wear compensation of the abrasive buffer of the axle buffer. In use, the abrasive wheels are worn down by the axle. By the application of a constant force of the buffing wheel against the axle surface, the wearing of the buffer wheel is compensated for.

[0066] The indictive proximity switch registers feedback to the CNC computer to enable a reference of the actual tool positioning and to also register the buffing wheel condemning limit to prevent collision during the buffing process. [0067] In use, the high pressure solenoid is activated and the ram 110 fully extended. The high pressure solenoid is turned off and the ram remains fully extended. The tool turret approaches the axle under direction from the CNC machine and continues to move until the buffer 92 touches the axle surface. Movement is continued until the inductive proximity sensor is activated. In the context of the present specification, this position is termed the last known probing position. It will be appreciated that this continued movement to the last known probing position results in a small portion (for example, 10 - 15 mm) of the ram 110 returning into the housing 112. Under control of the CNC machine, the buffer 92 then retreats from axle journal face.

[0068] The air motor 14 is activated and the buffer 92 begins rotating at a speed of about 3000 rpm in the opposite direction to the lathe. Under control of the CNC machine, the buffer 90 moves back to its last known probing position where the buffer is in contact with the journal surface. The low pressure solenoid is activated and applies the desired degree of pressure onto the axle journal surface. Under the control of the CNC machine, the buffer follows the programmed axle surface.

[0069] During normal operation, the buffer wheel will undergo wearing. As the buffer wheel wears and its radius decreases, the low pressure solenoid will maintain the pressure of the buffer wheel on the axle surface, causing a portion of the ram to extend from the housing. The distance that the portion of the ram that extends from the housing will mirror the distance the buffer wheel has worn. That is, if the radius of the buffer wheel has decreased by about 15 mm due to wearing, then about 15 mm of the ram will retract into the housing.

[0070] When the ram reaches the probing position (i.e. the distance that the ram extends from the housing), the CNC machine will move the axle buffer such that the buffer wheel no longer touches the axle surface.. The probing position thereby provides a safety measure that prevents the buffer wheel wearing excessively.