Remanufactured Hydraulic Device, Housing And Remanufacturing Method
Remanufacturing a variable displacement swash plate-type hydraulic device includes receiving a body of a used hydraulic device defining first and second actuator guide bores, at least one of which is out of specifications for guiding a swash plate linear actuator. The method further includes removing material forming the first and second guide bores, and interference fitting first and second sleeves into the body in place of the removed material. Additional material is removed from the first and second sleeves to form new first and second actuator guide bores, each satisfying specifications for guiding a swash plate linear actuator.
The present disclosure relates generally to the field of remanufacturing, and relates more particularly to installing sleeves in a hydraulic device body to form new guide bores for a swash plate linear actuator.
BACKGROUNDThe fields of machine component salvaging and remanufacturing have grown rapidly in recent years. Systems and components that only recently would have been scrapped are now repaired and/or refurbished and returned to service. For many years machine components have routinely been “rebuilt” and used again, but often only after the components' dimensions, operating characteristics or other features are modified out of necessity from original specs. It is more desirable in many instances for systems and components to be remanufactured to a condition as good or better than new. With this goal in mind, the development of remanufacturing strategies in certain technical areas has been rapid. In other areas, however, and in the case of certain specific parts, engineers continue to find it challenging to return components to a commercially and technically acceptable state, much less a condition identical to or better than that held in a former service life.
Chief among the challenges in successfully remanufacturing certain machine components is the difficulty in holding tolerances in a repair process. Geometric tolerancing and dimensional tolerancing are often relatively tightly specified for new parts. Where the new part consists of a casting or the like, it is often possible to machine features of interest on the new casting while held in a chuck or fixture in a single machining cell, and hence tight tolerances are more readily achievable. Machining for repair purposes and the like, however, often requires that the part be processed on multiple different machines, or with multiple different machining tools which cannot so readily be located and controlled as is the case with newly manufactured parts. For these and other reasons, successful remanufacturing strategies for many parts remain elusive. One known remanufacturing strategy for hydraulic pumps is set forth in commonly owned U.S. Pat. No. 7,934,303 to Awwad et al.
SUMMARYIn one aspect, a method of remanufacturing a variable displacement swash plate-type hydraulic device includes receiving a body of a used variable displacement swash plate-type hydraulic device defining a first and a second actuator guide bore each extending transverse to a longitudinal axis of the body, and at least one of which is out of specifications for guiding a swash plate linear actuator in the hydraulic device. The method further includes removing material of the body forming the first actuator guide bore via machining the body while supported in a first orientation upon a fixture, and removing material of the body forming the second actuator guide bore via machining the body while supported in a second orientation upon the fixture. The method further includes interference fitting a first and a second sleeve into the body in place of the removed material forming the first actuator guide bore and the removed material forming the second actuator guide bore, respectively. The method still further includes removing material of the first and second sleeves via machining the first and second sleeves to form new first and second actuator guide bores, respectively, each satisfying specifications for guiding a swash plate linear actuator in the hydraulic device.
In another aspect, a remanufactured housing for a variable displacement swash plate-type hydraulic device includes a body piece having formed therein a cavity extending between a first and a second body piece end, for receiving a fluid transferring mechanism that includes a rotatable shaft. The body piece further has formed therein a bearing bore located at the first body piece end configured to receive a bearing for journaling the rotatable shaft and defining a longitudinal axis extending between the first and second body piece ends. The body piece further includes a mounting flange located at the first body piece end, for mounting the hydraulic device, and a connecting flange located at the second body piece end, for connecting to another body piece of the remanufactured housing. The body piece further includes a first and a second actuator guide bore defined by a first and a second sleeve interference fitted into the body piece in place of material removed via machining The first and second actuator guide bores are oriented transverse to the longitudinal axis, radially offset from the longitudinal axis, and substantially coaxial with one another, such that the first and second actuator guide bores are positioned within the body piece for guiding a swash plate linear actuator coupled with the fluid transferring mechanism to vary the displacement of the hydraulic device.
In still another aspect, a remanufactured variable displacement swash plate-type hydraulic device includes a body piece having formed therein a cavity extending between a first and a second body piece end, and a bearing bore located at the first body piece end and defining a longitudinal axis extending between the first and second body piece ends. The hydraulic device further includes a fluid transferring mechanism having a rotatable shaft, positioned within the cavity, and a bearing positioned within the bearing bore and journaling the rotatable shaft. The body piece further includes a mounting flange located at the first body piece end, for mounting the hydraulic device, and a connecting flange located at the second body piece end. The hydraulic device further includes a first and a second sleeve interference fitted into the body piece and defining a first and a second actuator guide bore, respectively, the first and second actuator guide bores being oriented transverse to the longitudinal axis, radially offset from the longitudinal axis, and substantially coaxial with one another. The hydraulic device further includes a swash plate positioned within the cavity and contacting the fluid transferring mechanism, and a linear swash plate actuator having a first actuator end positioned within the first actuator guide bore, and a second actuator end positioned within the second actuator guide bore. The linear swash plate actuator is guided for linear movement within the first and second guide bores to adjust an angle of the swash plate so as to vary the displacement of the hydraulic device.
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As noted above, hydraulic device 10 includes a variable displacement hydraulic device. To this end, a swash plate 54 is positioned within cavity 16 and contacts mechanism 22, in particular piston and barrel assembly 52 in a conventional manner. Those skilled in the art will be well familiar with the general manner in which changing an angle of a swash plate can change displacement of a pump or motor. In
First sleeve 28 and second sleeve 30 are interference fitted into body piece 14 in place of material removed via machining Sleeves 28 and 30 may also be retained, or their retention enhanced, via a suitable adhesive such as Loctite® applied during installation. As noted above, when received after service in a machine system, it is common for originally designed-in actuator guide bores to have damage such as scuffing, scratches, or deformation so that they are out of round. Some of this damage may actually occur during the disassembly process, but in any event renders the corresponding actuator guide bore out of specifications for guiding a swash plate linear actuator. To return hydraulic device 10 to a state as good as or better than new, original equipment specifications must be satisfied, meaning that actuator guide bore damage must be repaired so that body piece 14 has actuator guide bores satisfying the specifications, along with all the other specifications relating to construction and functioning of hydraulic device 10.
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It will be recalled that the general probing and locating techniques discussed above enable linking the removal of material forming a first one of the existing actuator guide bores with removal of material forming a second one of the existing actuator guide bores. Such linking also enables machining of sleeve 28 to be relatively less intensive than what might otherwise be required. In other words, because the machining steps removing material of the first and second existing guide bores take place using the same X and Y positioning coordinates defined by a feature of fixture 175, the bores receiving sleeves 28 and 30 will tend to be quite close to being exactly coaxial. Sleeves 28 and 30 are machined to substantially final form prior to installation in body piece 14, and thus the final machining of sleeves 28 and 30 required to obtain the tight total runout tolerance is relatively modest. It may be noted that sleeve 30 has a single cylindrical inner surface 86 Inner surface 86 may define an inner diameter dimension prior to machining within body piece 14 of about 30 mm. Sleeve 28 includes a segmented inner surface, having a plurality of cylindrical inner surface segments 80, 82 and 84. Cylindrical inner surface 86 has a relatively lesser inner diameter dimension, and cylindrical surfaces 80, 82 and 84 have progressively larger inner diameter dimensions, and are all larger than the inner diameter dimension defined by inner surface 86. The inner diameter dimension defined by surface 80 may be about 75 mm, prior to machining within body piece 14. A chamfer 88 may be formed on an axial end of sleeve 28. It will typically be necessary to only machine inner surface 80 to result in sleeves 28 and 30, and thus bores 60 and 64, being coaxial within a total runout of about 0.006 mm as discussed above. Stated another way, specifications for guiding a swash plate linear actuator as discussed herein can be satisfied via machining only one of a plurality of inner surface segments 80, 82 and 84 of sleeve 28, typically just surface segment 80.
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The present description is for illustrative purposes only, and should not be construed to narrow the breadth of the present disclosure in any way. Thus, those skilled in the art will appreciate that various modifications might be made to the presently disclosed embodiments without departing from the full and fair scope and spirit of the present disclosure. Other aspects, features and advantages will be apparent upon an examination of the attached drawings and appended claims.
Claims
1. A method of remanufacturing a variable displacement swash plate-type hydraulic device comprising:
- receiving a body of a used variable displacement swash plate-type hydraulic device defining a first and a second actuator guide bore each extending transverse to a longitudinal axis of the body, and at least one of which is out of specifications for guiding a swash plate linear actuator in the hydraulic device;
- removing material of the body forming the first actuator guide bore via machining the body while supported in a first orientation upon a fixture;
- removing material of the body forming the second actuator guide bore via machining the body while supported in a second orientation upon the fixture;
- interference fitting a first and a second sleeve into the body in place of the removed material forming the first actuator guide bore and the removed material forming the second actuator guide bore, respectively; and
- removing material of the first and second sleeves via machining the first and second sleeves to form new first and second actuator guide bores, respectively, each satisfying specifications for guiding a swash plate linear actuator in the hydraulic device.
2. The method of claim 1 wherein the step of removing material of the first and second sleeves further includes removing material such that the new first and second actuator guide bores together satisfy a total runout specification.
3. The method of claim 2 wherein the step of removing material of the first and second sleeves includes removing material such that the new first and second actuator guide bores are coaxial within a total runout specification of about 0.006 millimeters.
4. The method of claim 2 further comprising a step of linking the removal of material forming the first guide bore with the removal of material forming the second guide bore.
5. The method of claim 4 wherein the step of linking further includes a step of locating an apparatus for the machining of the body via common positioning coordinates established in advance of each of the corresponding removing steps.
6. The method of claim 5 further comprising the steps of establishing X and Y positioning coordinates via probing the fixture a first time in advance of removing the material forming the first bore, and reestablishing the same X and Y positioning coordinates via probing the fixture a second time in advance of removing the material forming the second bore.
7. The method of claim 6 further comprising the steps of establishing a first Z positioning coordinate for locating the apparatus in the first removing step via probing a first surface extending circumferentially around the first bore, and establishing a second Z positioning coordinate for locating the apparatus in the second removing step via probing a second surface extending circumferentially around the second bore.
8. The method of claim 4 wherein the step of removing material of the first and second sleeves includes machining only one of a plurality of segments of an inner surface of the first sleeve to satisfy the specifications.
9. The method of claim 2 wherein the step of interference fitting further includes simultaneously press fitting the first and second sleeves into the body.
10. The method of claim 9 wherein the first sleeve is larger than the second sleeve, and wherein simultaneously press fitting further includes pushing the first sleeve into the body while pulling the second sleeve into the body using a common press fitting tool.
11. The method of claim 2 wherein the step of removing material of the first and second sleeves further includes removing the material with different machining heads of a common machining tool.
12. A remanufactured housing for a variable displacement swash plate-type hydraulic device comprising:
- a body piece having formed therein a cavity extending between a first and a second body piece end, for receiving a fluid transferring mechanism that includes a rotatable shaft;
- the body piece further having formed therein a bearing bore located at the first body piece end configured to receive a bearing for journaling the rotatable shaft and defining a longitudinal axis extending between the first and second body piece ends;
- the body piece further including a mounting flange located at the first body piece end, for mounting the hydraulic device, and a connecting flange located at the second body piece end, for connecting to a second body piece of the remanufactured housing;
- the body piece further including a first and a second actuator guide bore defined by a first and a second sleeve interference fitted into the body piece in place of material removed via machining; and
- the first and second actuator guide bores being oriented transverse to the longitudinal axis, radially offset from the longitudinal axis, and substantially coaxial with one another, such that the first and second actuator guide bores are positioned within the body piece for guiding a swash plate linear actuator coupled with the fluid transferring mechanism to vary the displacement of the hydraulic device.
13. The remanufactured housing of claim 12 wherein the first sleeve has a greater outer diameter dimension, and the second sleeve has a lesser outer diameter dimension.
14. The remanufactured housing of claim 13 wherein the first and second sleeves are coaxial with one another within a total runout of about 0.006 millimeters.
15. The remanufactured housing of claim 14 wherein the first sleeve has a segmented inner surface defining a plurality of different inner diameter dimensions.
16. The remanufactured housing of claim 15 wherein the second sleeve has a non-segmented inner surface defining a single inner diameter dimension less than the plurality of different inner diameter dimensions, and a radially projecting end flange recessed within the body piece.
17. The remanufactured housing of claim 14 wherein the body piece further has formed therein a first set of fastener bores extending through the connecting flange in an axial direction, a second set of fastener bores distributed about the first sleeve and extending in a transverse direction, and a third set of fastener bores distributed about the second sleeve and extending in the transverse direction.
18. A remanufactured variable displacement swash plate-type hydraulic device comprising:
- a body piece having formed therein a cavity extending between a first and a second body piece end, and a bearing bore located at the first body piece end and defining a longitudinal axis extending between the first and second body piece ends;
- a fluid transferring mechanism including a rotatable shaft, positioned within the cavity;
- a bearing positioned within the bearing bore and journaling the rotatable shaft;
- the body piece further including a mounting flange located at the first body piece end, for mounting the hydraulic device, and a connecting flange located at the second body end;
- a first and a second sleeve interference fitted into the body piece and defining a first and a second actuator guide bore, respectively, the first and second actuator guide bores being oriented transverse to the longitudinal axis, radially offset from the longitudinal axis, and substantially coaxial with one another;
- a swash plate positioned within the cavity and contacting the fluid transferring mechanism; and
- a linear swash plate actuator having a first actuator end positioned within the first actuator guide bore, and a second actuator end positioned within the second actuator guide bore, and being guided for linear movement within the first and second guide bores to adjust an angle of the swash plate so as to vary the displacement of the hydraulic device.
19. The remanufactured hydraulic device of claim 18 comprising a pump wherein the fluid transferring mechanism includes a piston and barrel assembly.
20. The remanufactured hydraulic device of claim 19 wherein the first and second sleeves are coaxial with one another within a total runout of about 0.006 millimeters.
Type: Application
Filed: Jun 11, 2013
Publication Date: Dec 11, 2014
Inventors: Donald Clark (Iuka, MS), Joseph W. Louks (Summerville, SC), Robert Lovenshimer (Summerville, SC), John Charpia (Summerville, SC)
Application Number: 13/915,104
International Classification: F04B 1/29 (20060101);