Title of Invention

METHOD OF PRODUCING A HOLLOW SHAFT

Abstract

The invention relates to a hollow shaft (1) which on both ends has external profiling (2, 3) for the transmission of torque, shaft sections (4) lying therebetween having a smaller diameter than at least one of the profiled sections. The hollow shaft (1) can be or is assembled from two components (4, 12), one of which contains the shaft section (4) and the profile, as well as an outer, torque-transmitting profile (5) of a plug-in connector on the opposite side of the shaft to the profile, the other component being a bush-type component (12) with the second profile and an inner, torque-transmitting profile (6) of a plug-in connector.

Full Text

FORM 2 THE PATENT ACT 1970 (39 of 1970) The Patents Rules, 2003 COMPLETE SPECIFICATION (See Section 10, and rule 13) 1. TITLE OF INVENTION HOLLOW SHAFT AND METHOD OF PRODUCING THE SAME 2. APPLICANT(S) a) Name : NEUMAYER TEKFOR HOLDING GMBH b) Nationality : GERMAN Company c) Address : WILHELM-ZANGEN-STR.9, 77756 HAUSACH GERMANY 3. PREAMBLE TO THE DESCRIPTION The following specification particularly describes th invention and the manner in which it is to be performed : ENGLISH TRANSLATION VARIFICATION CERTIFICATE u/r. 20(3)(b) I, Mr. HIRAL CHANDRAKANT JOSHI, an authorized agent for the applicant, NEUMAYER TEKFOR HOLDING GMBH do hereby verify that the content of English translated complete specification filed in pursuance of PCT International application No. PCT/DE06/001544 thereof is correct and complete. The invention relates to a hollow shaft, which has external profilings for torque transmission at its two ends, e.g., splines, wedge-shaped teeth, polygonal profiles or the like, such that the shaft sections there between have a smaller diameter than the profilings. Hollow shafts of this type can be used to drive units such as oil pumps, where, for space reasons, the center section is thinner than the toothed ends. One proposed method to produce such shafts was to form them as a single part using cold extrusion. In this case, however, one of the profilings would have to be re-expanded after the forming of the hollow shaft section. Such expansions can only be done in special, highly complex tools and require a substantial amount of additional work thereafter. This would have caused substantial additional costs. It was therefore an object of the present invention to provide a hollow shaft of the above-described type, which is distinguished by its particularly simple, cost-effective and rapid manufacture and high precision. A further object was to provide methods for its cost-effective, rapid and precise production. According to the invention, these objects are achieved by a shaft assemblable or assembled from two components, one of which comprises the hollow shaft section and the one profile as well as an external torque-transmitting slip joint on the shaft side opposite the profile, and the other of which is a sleeve-like component having the second profile and an internal torque-transmitting profile of a slip joint. It is advantageous if the hollow-shaft-type section, the profilings and the one profile of the slip joint of the one component and/or the other component are formed from a solid blank using cold extrusion. - 2- It can be advantageous if an interference fit is provided between the internal and external profiles of the slip joint to prevent the sleeve from falling off the shaft-like section after mounting during transport, handling or assembly. If the two profilings provided on the shaft ends have different diameters, it is advantageous if the smaller profiling is provided on the sleeve-like component and the larger profiling is integrally formed with the tubular section. To produce the hollow shaft section with a torque-transmitting profiling, such as an external spline profile, which is formed at its one end and has a larger diameter than the shaft diameter, and a torque-transmitting external profile of a slip joint provided on the opposite shaft end, it is advantageous to provide at least some of the process steps listed below: a) Cutting a material blank from bar stock to length, b) A first cupping to form a cup-like hollow region with a solid extension, such that the cup region corresponds at least approximately to the inside and the outside diameter of the profile section, c) A second cupping to lengthen the hollow region from the extension using cold extrusion, d) Perforating the cup's bottom, e) Tube extrusion to begin to form the hollow shaft body using cold extrusion, f) A first reduction of the diameter and the wall thickness and lengthening of the hollow shaft section produced in step e) and forming a neck portion that is thicker than the outside hollow shaft - 3- diameter adjoining the region intended to form the profiling, using cold extrusion, g) A second reduction starting at least approximately from the annular neck portion and lengthening of the hollow shaft section produced in step f) using cold extrusion, h) Final pressing by cold extrusion of the profile region to form the external teeth by inserting a mandrel into the internal contour of the profile region with the same diameter, such that an annular die surrounding the mandrel penetrates the end face of the end region and thereby displaces material into the counterteeth of a die placed around the region intended to form the teeth, thereby forming an axial projection, i) Optionally and simultaneously with step h), producing the external profile of the slip joint in the region of the hollow shaft opposite the profile region using cold extrusion, j) Removing the projection by turning. To produce the bushing with the external profiling and an internal profile of a slip joint, at least some of the process steps listed below can be particularly advantageous: a) Cutting a material blank from bar stock to length, b) Cupping and simultaneously forming the internal profile of the slip joint, preferably to the finished profile dimension, using cold extrusion, c) Perforating the cup's bottom, - 4- d) Turning the outside diameter, e) Producing the external profile using cold extrusion by inserting a mandrel with a profile corresponding to the internal profile of the slip joint into the internal profile, such that an annular die surrounding the mandrel penetrates the end face opposite the perforated bottom and thereby displaces material into the counterteeth of a die previously placed around the region intended to form the external profile, thereby forming an axial projection, f) Turning the bushing height to the finished dimensions and thereby removing the axial projection. For the further production of a hollow shaft at least three of the steps listed below can be particularly advantageous, either before or after mounting or pressing the sleeve onto the shaft via the slip joint: a) Turning the portion within the profile region formed integrally with the shaft profile to form a bearing seat, b) Forming a recess in the outer end region of the profile, c) Forming a chamfer at the beginning of the internal contour in the region of the profile, d) Forming an undercut in the end region of the cylindrical internal contour in the region of the profile. It can be advantageous to carry out a heat treatment or surface treatment, particularly soft annealing, between some of the process steps to resoften the material whose structure was hardened by cold forming in the previous steps, e.g., - 5- when producing the hollow shaft body with the first profile formed onto it, between steps b) and c), d) and e), e) and f), f) and g), and g) and h), or, when producing the sleeve, between steps d) and e). The invention will now be described in more detail with reference to Figures 1 to 19. Figure 1 shows a hollow shaft according to the invention or a hollow shaft produced using a method according to the invention, Figures 2 to 19 illustrate the different process steps to produce a shaft like the one shown in Figure 1. The oil pump shaft 1 shown in Figure 1 is a hollow shaft and has external profilings at its ends in the form of shaft profilings or splines 2,3. Between the two profile zones 2, 3 is a tubular section 4, which, at least in partial areas, has a smaller diameter than the profilings 2,3. In the present example, profile 3 and the tubular section 4 are formed integrally or as a single part. Sleeve 7, which is provided with profile 2, is mounted to the end of the shaft opposite profile 3 via a torque-transmitting slip joint 5, 6, which will be described in more detail below. The slip joint 5, 6 is configured as an interference fit. The tubular section 4 and the profile section 3 integrally formed therewith as well as the sleeve 7 are produced by cold forming as described below, at least with respect to their functional areas. Figure 2 shows a blank 8 cut to length from bar stock, in this case by sawing. Using a cold extrusion process, a component 9 is produced from this blank in a process step labeled “Cupping I” in Figure 3. - 6- The sleeve-like part identified by 10 in Figure 4 is produced by cold extrusion in a process step labeled "Cupping II." In a process step labeled "Perforation," the bottom 11 (see Figure 4) of the sleeve-like component 10 is removed to create a component 12 without a bottom as illustrated in Figure 5. In a process step labeled "Tube extrusion," material is essentially displaced from region 13 as shown in Figure 5 to produce the hollow region 14 of component 15 as illustrated in Figure 6. In the process step labeled "Reduction I," the hollow shaft section 16 of component 17 illustrated in Figure 7 is essentially produced from the region 14 shown in Figure 6. A neck portion 18 adjoining the region intended to create the profile 3 is also formed. In a subsequent process step labeled "Reduction II," the section identified as 16 in Figure 7 is tapered by cold extrusion starting at least approximately from the neck-shaped portion 18 shown there, and the hollow shaft section 20 of a component 21 is produced as shown in Figure 8. In the process step labeled "Final pressing" the component 22 shown in Figure 9 is provided with the external profiling 3 clearly visible in Figure 10, which shows an enlarged detail X of Figure 9. In the same process step, profiling 5, i.e., a polygon for a torque-transmitting slip joint can be formed at the ends of the hollow shaft section 23 opposite splines 3. This detail is illustrated in an enlargement depicted in Figure 11, which shows a section taken along line XI of Figure 9. Profiling 3 is formed by placing a die, which is provided with a counterprofiling, around the region identified as 19 in Figure 8. A mandrel is then inserted into the interior contour of region 19 and an annular die a part of which, identified as 25, - 7- is shown in Figure 10 drives against the end face 26 (see Figure 8), penetrates region 19 and displaces material into the teeth of the die to form teeth 3. In this process, a projection 27 is also formed, as may be seen particularly in Figure 10. The projection 27 is removed by turning at line 28 in the process step labeled "Length turning" as illustrated in Figure 12 to form the hollow shaft with its region 4 and the splined region 3 integrally provided thereon and with the external profile 6 of a slip joint as shown in Figure 1. The sleeve 7 with external profile 2 and external profile 6 of a slip joint is produced as illustrated in Figures 13 to 19. In the process step labeled "Sawing" a blank 30 is formed as illustrated in Figure 13. A cup-shaped component 31 with a cylindrical region 32 and a bottom 33 is produced in the process step labeled "Cupping" illustrated in Figure 14. In the process step shown in Figure 14 the internal profile 5 of the torque-transmitting slip joint is produced in the form of a polygon in the cold extrusion step illustrated in Figure 14. Profiling 5 is clearly visible in Figure 15, which shows a view in the direction of arrow XV-XV in Figure 14. In the process step illustrated in Figure 16, which is labeled "Perforation," the bottom 33 (Figure 15) is partly removed. In the process step illustrated in Figure 17 and identified as "Turning 1," the outside diameter 34 of the sleeve-like component 7 is turned. In the process step shown in Figure 19 labeled "Tooth reduction," the external profile 2 is produced in essentially the same manner as profile 3 in the process step illustrated in Figure 9. - 8- In the process step in which sleeve 7 is provided with the toothed profile 2 shown in Figure 19, a mandrel corresponding to profiling 5 is again axially inserted into profile 5 and an annular die 35 drives against the end face 36 (Figure 18), such that material from the end face region is displaced by cold extrusion into the counterprofile of a die, which is provided with the countershape of profiling 2 and which is placed around the cylindrical outside diameter 34. A projection 37 created in this process is removed in a process step labeled "Turning 2," which is illustrated in Figure 19. Region 38, which may serve as a bearing seat, can be formed by turning before, or even after, assembly of components 4 and 7. A recess 39 is turned in the outer end region of profile 3. Likewise, a chamfer 40 and an undercut 41 are turned at the end of the cylindrical region 38. - 9- WE CLAIM: 1. A hollow shaft having improved profilings such as external splines, which are provided for torque transmission at its two ends, wherein shaft sections therebetween have smaller diameters than at least one of the profilings, characterized in that the hollow shaft is assemblable or assembled from two components, one of which comprises the shaft section and the profile and on the side of the shaft opposite said profile an external torque-transmitting profile of a slip joint, and wherein the other component is a sleeve-like component with the second profile and an internal torque-transmitting profile of a slip joint. 2. A hollow shaft as claimed in claim 1, characterized in that the hollow shaft- type section, the profiling and the one profile of the slip joint and/or the other component are formed from a solid blank using cold extrusion. 3. A hollow shaft as claimed in claim 1 or 2, characterized in that an interference fit is provided between the internal and the external profile of the slip joint. 4. A hollow shaft as claimed in any one of claims 1 to 3, in which the profilings provided at the ends thereof have different diameters, characterized in that the profiling on the sleeve-like component has a smaller diameter. 5. A method of producing a hollow shaft, particularly as claimed in any one of claims 1 to 4, characterized in that a hollow shaft section, which has a torque-transmitting profiling such as external splines at its one end which has a larger diameter than the shaft diameter and an external torque-transmitting profile of a slip joint at its opposite shaft end, is produced by executing at least some of the following steps: -10- a) Cutting a material blank from bar stock, b) A first cupping wherein a cup-like hollow region with a solid extension is formed by cold extrusion and wherein the cup region corresponds at least approximately to the inside diameter and the outside diameter of the profile section, c) A second cupping, wherein the hollow region is lengthened from the extension by cold extrusion, d) Perforation of the cup's bottom, e) Tube extrusion to begin to form the hollow shaft body by cold extrusion, f) A first reduction of the diameter and wall thickness as well as lengthening of the hollow shaft section and forming a neck portion that is thicker than the outside hollow shaft diameter adjoining the region intended to form the profiling using cold extrusion, g) A second reduction starting from at least approximately the neck-like portion and lengthening of the hollow shaft section using cold extrusion, h) Final pressing of the profile region in the form of external teeth by inserting a mandrel into the internal contour in the profile region with the same diameter, wherein an annular die surrounding the mandrel penetrates the end face of the end region and thereby displaces material into the counterteeth of a -11- die, which is placed around a region intended to form the teeth, thereby forming an axial projection by cold extrusion, i) Optionally and simultaneously with step h), forming the external profile of the slip joint in the section of the hollow shaft opposite the profile region using cold extrusion, j) Removing the projection by turning. 6. A hollow shaft as claimed in claim 5, characterized in that a heat treatment, particularly soft annealing, is carried out between some of the steps, preferably between steps b) and c), d) and e), e) and f), f) and g), and g) and h). 7. Method of producing a bushing with external profiling and an internal profile of a slip joint, particularly for a component as claimed in any one of claims 1 to 6, characterized by at least some of the following production steps: a) Cutting a material blank from bar stock to length, b) Cupping and simultaneously forming the internal profile of the slip joint, preferably to the finished profile dimensions, using cold extrusion, c) Perforating the bottom, d) Turning the outside diameter, -12- e) Producing the external profile using cold extrusion, wherein a mandrel with a profile corresponding to the internal profile of the slip joint is inserted into said internal profile, and an annular die surrounding the mandrel penetrates the end face opposite the perforated bottom and thereby displaces material into the counterteeth of a die, which was placed around the region intended to form the teeth, thereby forming an axial projection, f) Turning the bushing height to the finished dimensions and simultaneously removing the axial projection. 8. A method for producing a hollow shaft, particularly as claimed in any one of claims 1 to 7, characterized by at least two of the following steps, before or after mounting or pressing the sleeve onto the shaft via the slip joint: a) Turning a portion within the profile formed integrally with the shaft profile, b) Forming a recess in the outer end region of the profile, c) Forming a chamfer at the beginning of the internal contour in the region of the profile, d) Forming an undercut in the end region of the cylindrical internal contour in the region of the profile. -13- 9. A hollow shaft as claimed in claim 7, characterized in that a heat treatment, particularly soft annealing, is carried out between some of the steps, preferably between steps d) and e). Dated this 27th day of March 2008. -14- ABSTRACT The invention relates to a hollow shaft (1) which on both ends has external profiling (2, 3) for the transmission of torque, shaft sections (4) lying therebetween having a smaller diameter than at least one of the profiled sections. The hollow shaft (1) can be or is assembled from two components (4, 12), one of which contains the shaft section (4) and the profile, as well as an outer, torque-transmitting profile (5) of a plug-in connector on the opposite side of the shaft to the profile, the other component being a bush-type component (12) with the second profile and an inner, torque-transmitting profile (6) of a plug-in connector. To The Controller of Patents The Patent office -15- Mumbai.

Documents:

578-MUMNP-2008-ABSTRACT(3-10-2013).pdf

578-mumnp-2008-abstract.doc

578-mumnp-2008-abstract.pdf

578-MUMNP-2008-CANCELLED PAGES(27-7-2011).pdf

578-MUMNP-2008-CLAIMS(AMENDED)-(27-7-2011).pdf

578-MUMNP-2008-CLAIMS(AMENDED)-(3-10-2013).pdf

578-mumnp-2008-claims.doc

578-mumnp-2008-claims.pdf

578-MUMNP-2008-CORRESPONDENCE 7-7-2008.pdf

578-MUMNP-2008-CORRESPONDENCE(01-09-2008).pdf

578-MUMNP-2008-CORRESPONDENCE(27-08-2008).pdf

578-MUMNP-2008-CORRESPONDENCE(27-7-2011).pdf

578-mumnp-2008-correspondence(7-7-2008).pdf

578-mumnp-2008-correspondence-others.pdf

578-mumnp-2008-correspondence-received.pdf

578-mumnp-2008-description (complete).pdf

578-mumnp-2008-drawings.pdf

578-MUMNP-2008-ENGLISH TRANSLATION(27-7-2011).pdf

578-MUMNP-2008-FORM 1(3-10-2013).pdf

578-mumnp-2008-form 1(7-7-2008).pdf

578-MUMNP-2008-FORM 2(TITLE PAGE)-(3-10-2013).pdf

578-mumnp-2008-form 2(title page)-(complete)-(27-3-2008).pdf

578-MUMNP-2008-FORM 26(3-10-2013).pdf

578-MUMNP-2008-FORM 3(27-7-2011).pdf

578-MUMNP-2008-FORM 3(3-10-2013).pdf

578-MUMNP-2008-FORM 5(27-7-2011).pdf

578-MUMNP-2008-FORM PCT-IB-304(27-7-2011).pdf

578-mumnp-2008-form-1.pdf

578-mumnp-2008-form-18.pdf

578-mumnp-2008-form-2.doc

578-mumnp-2008-form-2.pdf

578-mumnp-2008-form-26.pdf

578-mumnp-2008-form-3.pdf

578-mumnp-2008-form-5.pdf

578-mumnp-2008-form-pct-ib-304.pdf

578-MUMNP-2008-MARKED COPY(3-10-2013).pdf

578-MUMNP-2008-OTHER DOCUMENT(3-10-2013).pdf

578-MUMNP-2008-OTHER DOCUMENTS(01-09-2008).pdf

578-MUMNP-2008-PCT-ISA-237(01-09-2008).pdf

578-mumnp-2008-pct-search report.pdf

578-MUMNP-2008-PETITION UNDER RULE 137(27-7-2011).pdf

578-MUMNP-2008-REPLY TO EXAMINATION REPORT(27-7-2011).pdf

578-MUMNP-2008-REPLY TO HEARING(3-10-2013).pdf

578-mumnp-2008-wo international publication report(27-8-2008).pdf

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