JP2009121529A - Method for production of expandable shaft, and expandable shaft produced by the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for production of an expandable shaft in which lubricant is smoothly fed to a sliding surface, the sliding resistance is maintained small for a long time, and the lifetime of the expandable shaft is enhanced, and to provide the expandable shaft produced by the method. <P>SOLUTION: A covered part 61 is formed over the entire length in the axial direction of a tooth of a male shaft 16A, and a groove of a female shaft 16B is housed over the entire length in the axial direction of a tooth 1 of the male shaft 16A. Next, the load P in the direction orthogonal to the axis of the female shaft 16B is applied to an upper end of the male shaft 16A. As a result, the male shaft 16A is relatively folded with respect to the female shaft 16B. Thus, a part Q and a part R in a vicinity of both ends in the axial direction of the covered part 61 are strongly compressed, and chamfered portions 62, 62 are formed in a vicinity of both ends in the axial direction of the covered part 61. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a telescopic shaft, particularly a telescopic shaft capable of transmitting rotational torque and capable of sliding relative to the axial direction, for example, a telescopic shaft such as an intermediate shaft or a steering shaft, and a telescopic shaft manufactured by the manufacturing method. About.

  In the steering device, a telescopic shaft such as a spline shaft that is connected so as to be capable of transmitting rotational torque and is relatively slidable in the axial direction is incorporated in an intermediate shaft, a steering shaft, or the like. In other words, when the universal joint is fastened to the pinion shaft that meshes with the rack shaft of the steering gear, the intermediate shaft is temporarily contracted and then fitted to the pinion shaft and fastened. In order to absorb water, an expansion / contraction function is required.

  In addition, the steering shaft transmits the steering force of the steering wheel to the wheel, and the position of the steering wheel needs to be adjusted in the axial direction according to the physique and driving posture of the driver. .

  In recent years, the rigidity and running stability of the entire vehicle body have been improved, so that when the steering wheel is operated, it becomes easier for the driver to feel rattling in the rotational direction of the telescopic shaft. Therefore, there is a demand for an expansion / contraction shaft that has small backlash in the rotational direction and is excellent in lubricity and durability.

  For this purpose, there is a telescopic shaft that is fitted to the female shaft after coating a resin having a small sliding resistance on the outer periphery of the tooth surface of the male shaft and applying a lubricant for lubrication. Since such a telescopic shaft repeatedly expands and contracts while a torque is applied during vehicle operation, it is necessary to constantly supply a lubricant (oil) to the contact portion between the tooth surfaces of the male shaft and the female shaft.

  The telescopic shaft of Patent Document 1 applies rotational torque in a state where the female shaft is fitted to the male shaft coated with resin, and presses the inner teeth of the female shaft against the resin-coated portion of the outer teeth of the male shaft. It hardens | cures and forms the press dent surface in the resin coating part. Accordingly, the sliding gap is kept constant over a long period of time, and the lubricant is stored in the pressing recess surface, so that the supply of the lubricant is improved. However, since the telescopic shaft of Patent Document 1 has a pressing depression surface, there is a problem in that a gap is formed between the inner teeth of the female shaft and the outer teeth of the male shaft, causing backlash in the rotational direction.

  In the state where the female shaft is fitted to the male shaft coated with the resin, the telescopic shaft of Patent Document 2 is softened by heating the resin from the outside to form a gap between the internal teeth of the female shaft and the external teeth of the male shaft. The resin coating is molded. As a result, the meshing gap between the inner teeth and the outer teeth is made uniform, the play in the rotational direction is reduced, and the sliding resistance in the axial direction is improved. However, the telescopic shaft disclosed in Patent Document 2 has a problem in that rattling occurs in the rotational direction because there is a meshing gap between the inner teeth of the female shaft and the outer teeth of the male shaft.

  Moreover, since the both ends of the axial direction of the coating | coated part of a male shaft become an edge in the expansion-contraction shaft of the said patent document 1 and the patent document 2, the lubricant apply | coated to the contact part of the tooth surface of a male shaft and a female shaft is carried out. The edge of the covering part is swept out of the contact part, the supply of the lubricant is insufficient, the sliding resistance increases, and the life of the telescopic shaft may decrease.

JP 2004-66970 A JP 2002-321627 A

  The present invention relates to a telescopic shaft having a covering portion that reduces sliding resistance, wherein the lubricant is smoothly supplied to the sliding surface, the sliding resistance is kept small over a long period of time, and the life of the telescopic shaft is improved. It is an object of the present invention to provide a method for manufacturing a telescopic shaft and a telescopic shaft manufactured by the manufacturing method.

  The above problem is solved by the following means. That is, the first invention is a male shaft having a non-circular outer peripheral shape, and a non-circular inner peripheral shape that is fitted on the outer periphery of the male shaft so as to be capable of relative sliding in the axial direction and to transmit rotational torque. A method of manufacturing a telescopic shaft having a covering portion that is formed over the entire axial length of a non-circular outer periphery of the male shaft, and that reduces a sliding resistance between the inner periphery of the female shaft, A step of forming a covering portion for reducing sliding resistance between the inner periphery of the female shaft and the non-circular outer periphery of the male shaft on which the covering portion is formed; A step of fitting the non-circular inner periphery of the female shaft to the entire length in the axial direction, applying a load in a direction of bending the male shaft relative to the female shaft, Near both axial ends The covering portion by compressing a method for manufacturing a telescopic shaft, characterized in that it comprises a step of forming a chamfered portion.

  According to a second aspect of the present invention, in the method for manufacturing the telescopic shaft of the first aspect, the covering portion is heated while applying a load in a direction in which the male shaft is bent relative to the female shaft. It is a manufacturing method of the telescopic shaft.

  A third aspect of the invention is a method for manufacturing an extendable shaft according to the second aspect of the invention, wherein the covering portion is heated to 30 degrees or more.

  According to a fourth aspect of the present invention, in the method for manufacturing the telescopic shaft of the first aspect, the male shaft is attached to the female shaft while applying a load in a direction of bending the male shaft relative to the female shaft. It is a manufacturing method of an expansion-contraction shaft characterized by making it slide relatively in an axial direction.

  According to a fifth aspect of the present invention, in the method for manufacturing the telescopic shaft of the first aspect, the male shaft is attached to the female shaft while applying a load in a direction in which the male shaft is bent relative to the female shaft. It is a manufacturing method of an expansion-contraction shaft characterized by carrying out a razor movement relatively.

  According to a sixth aspect of the present invention, in the method of manufacturing the telescopic shaft according to the first aspect, the load in the direction of bending the male shaft relative to the female shaft is a plurality of angular positions in the circumferential direction of the male shaft. It is the manufacturing method of the expansion-contraction shaft characterized by the above-mentioned.

  According to a seventh aspect of the present invention, in the method for manufacturing the telescopic shaft of the first aspect, a step of applying a load in a direction of bending the male shaft relative to the female shaft, and a male shaft relative to the female shaft The method of manufacturing the telescopic shaft is characterized in that the steps of sliding the shaft in the axial direction are sequentially performed.

  According to an eighth aspect of the present invention, in the method for producing a telescopic shaft according to any one of the first to seventh aspects, the covering portion is at least one of rubber, a polymer material, and a solid lubricant. It is a manufacturing method of the expansion-contraction shaft characterized by being formed with the material.

  A ninth aspect of the invention is a telescopic shaft manufactured by the manufacturing method of the telescopic shaft according to any one of the first to eighth aspects of the invention.

  A tenth aspect of the invention is a male shaft having a non-circular outer peripheral shape, and a female having a non-circular inner peripheral shape that is fitted on the outer periphery of the male shaft so as to be capable of relative sliding in the axial direction and to transmit rotational torque. A telescopic shaft formed over the entire axial length of a non-circular inner periphery of the female shaft, and having a covering portion for reducing sliding resistance with the outer periphery of the male shaft, A step of forming a covering portion for reducing sliding resistance between the outer circumference of the male shaft on the entire axial length of the circular inner circumference, and a female shaft having the covering portion formed on the non-circular outer circumference of the male shaft. A step of externally fitting the entire axial length of the noncircular inner circumference, applying a load in a direction of bending the male shaft relative to the female shaft, and both axial ends of the noncircular inner circumference of the female shaft Compress the surface of the nearby coating Ri unit is a telescopic shaft produced by forming a.

  In the manufacturing method of the telescopic shaft of the present invention and the telescopic shaft manufactured by this manufacturing method, the coating that reduces the sliding resistance between the inner periphery of the female shaft to the entire axial length of the non-circular outer periphery of the male shaft The step of forming a portion, the step of fitting the non-circular inner periphery of the female shaft to the entire axial length of the non-circular outer periphery of the male shaft on which the covering portion is formed, and the male shaft relative to the female shaft A step of forming a chamfered portion by applying a load in a bending direction and compressing the covering portion in the vicinity of both axial ends of the non-circular outer periphery of the male shaft.

  Therefore, since the chamfered portions are formed at both end portions in the axial direction of the covering portion, the lubricating oil applied to the sliding surface is not swept out of the sliding surface. Therefore, the lubricant is smoothly supplied to the sliding surface, the sliding resistance is kept small for a long time, and the life of the telescopic shaft is improved.

  Embodiments 1 to 5 of the present invention will be described below with reference to the drawings.

  FIG. 1 is a side view of the steering device having the telescopic shaft according to the present invention, partially cut away, showing an embodiment applied to an electric power steering device having a steering assisting portion. FIG. 2 is a longitudinal sectional view showing the main part of the telescopic shaft of the first embodiment of the present invention. 3 is an AA enlarged cross-sectional view of FIG. 2, wherein (1) is an enlarged cross-sectional view showing a telescopic shaft coated with a sleeve, and (2) is an enlarged cross-sectional view showing a telescopic shaft coated with a covering portion.

  FIGS. 4A and 4B are explanatory views showing the production process of the telescopic shaft according to the first embodiment of the present invention. FIG. 4A is a longitudinal sectional view of the main part of the telescopic shaft, and FIG. 4B is a top view of FIG. FIG. 5 is a perspective view showing the male shaft of the telescopic shaft according to the first embodiment of the present invention. 6 shows a telescopic shaft male shaft manufactured by the manufacturing method of Embodiment 1 of the present invention, (1) is a vertical sectional view of the male shaft alone, and (2) is an enlarged sectional view of S part of (1). .

  As shown in FIG. 1, the steering device having the telescopic shaft of the embodiment of the present invention has a steering shaft 12 on which a steering wheel 11 can be mounted on the rear side of the vehicle body (right side in FIG. 1), and this steering shaft 12 is inserted. A steering column 13, an assist device (steering assisting portion) 20 for applying auxiliary torque to the steering shaft 12, and a vehicle front side (left side in FIG. 1) of the steering shaft 12 via a rack / pinion mechanism (not shown). And a connected steering gear 30.

  The steering shaft 12 is formed by combining a female shaft 12A and a male shaft 12B so that rotational torque can be transmitted and relative displacement can be performed in the axial direction.

  That is, a plurality of male splines are formed on the outer periphery on the vehicle body rear side of the male shaft 12B, and a plurality of female splines are formed on the inner periphery on the vehicle body front side of the female shaft 12A at the same phase position as the male spline. The male spline of the male shaft 12B is externally fitted with a predetermined gap, and is engaged so as to be able to transmit rotational torque and be relatively displaceable in the axial direction. Therefore, the engaging portion of the female shaft 12A and the male shaft 12B can slide relative to each other at the time of collision, so that the overall length can be shortened.

  Further, the cylindrical steering column 13 inserted through the steering shaft 12 combines the outer column 13A and the inner column 13B so that they can be telescopically moved. It has a so-called collapsible structure in which the entire length is shortened while absorbing water.

  The vehicle body front side end portion of the inner column 13B is press-fitted and fixed to the vehicle body rear side end portion of the gear housing 21. Further, the vehicle body front side end portion of the male shaft 12B is passed through the inside of the gear housing 21 and is coupled to the vehicle body rear side end portion of the input shaft (not shown) of the assist device 20.

  The steering column 13 is supported by a support bracket 14 at a middle portion thereof on a part of the vehicle body 18 such as a lower surface of the dashboard. Further, a locking portion (not shown) is provided between the support bracket 14 and the vehicle body 18, and when an impact in a direction toward the front side of the vehicle body is applied to the support bracket 14, the support bracket 14 is locked to the locking bracket 14. It moves away from the vehicle and moves to the front side of the vehicle.

  The upper end portion of the gear housing 21 is also supported on a part of the vehicle body 18. In the case of this embodiment, by providing a tilt mechanism and a telescopic mechanism, the position of the steering wheel 11 in the longitudinal direction of the vehicle body and the height position can be freely adjusted. Such a tilt mechanism and a telescopic mechanism are well known in the art and are not characteristic features of the present invention, and thus detailed description thereof is omitted.

  The output shaft 23 protruding from the end face on the vehicle body front side of the gear housing 21 is connected to a rear end portion of a male intermediate shaft (hereinafter referred to as a male shaft) 16A of the intermediate shaft 16 through a universal joint 15. Further, an input shaft 31 of the steering gear 30 is connected to a front end portion of a female intermediate shaft (hereinafter referred to as a female shaft) 16B of the intermediate shaft 16 via another universal joint 17.

  The male intermediate shaft 16A is coupled to the female intermediate shaft 16B so as to be capable of relative sliding in the axial direction and to transmit rotational torque. A pinion (not shown) is formed at the front end of the input shaft 31. A rack (not shown) meshes with the pinion, and the rotation of the steering wheel 11 moves the tie rod 32 to steer a wheel (not shown).

  A case 261 of an electric motor 26 is fixed to the gear housing 21 of the assist device 20. The direction and magnitude of torque applied from the steering wheel 11 to the steering shaft 12 is detected by a torque sensor. In response to this detection signal, the electric motor 26 is driven to cause the output shaft 23 to generate auxiliary torque with a predetermined magnitude in a predetermined direction via a speed reduction mechanism (not shown).

  As shown in FIG. 2, the telescopic shaft according to the first embodiment of the present invention is applied to the male shaft 16 </ b> A and the female shaft 16 </ b> B of the intermediate shaft 16. The vehicle body front side (lower end in FIG. 2) of the male shaft 16A is fitted and connected to the vehicle body rear side (upper end in FIG. 2) of the female shaft 16B.

  As shown in FIG. 2, FIG. 3 (1), (2), the female shaft 16B formed of carbon steel or aluminum alloy is formed in a hollow cylindrical shape, and the inner periphery of the female shaft 16B is an axis of the female shaft 16B. A plurality of axial grooves 41 are formed at equal intervals over the entire length of the expansion / contraction stroke, radially from the center.

  In the example of FIG. 3A, the sliding resistance between the teeth 51 of the male shaft (male spline shaft) 16A formed of carbon steel or aluminum alloy and the groove 41 of the female shaft (female spline cylinder) 16B is shown. An example of a telescopic shaft covered with a sleeve is shown as the covering portion 61 to be reduced. That is, the male shaft 16A having four axial teeth 51 as a non-circular outer peripheral shape for transmitting rotational torque has a total length in the axial direction of the teeth 51 between the groove 41 of the female shaft 16B. A sleeve is covered as a covering portion 61 that reduces the sliding resistance of the sleeve.

  In the example of FIG. 3 (2), the covering portion 61 for reducing the sliding resistance between the teeth 51 of the male shaft (male spline shaft) 16A and the groove 41 of the female shaft (female spline cylinder) 16B is coated. An example of the extended telescopic axis is shown. That is, the male shaft 16A having 18 axial teeth 51 as a non-circular outer peripheral shape for transmitting rotational torque has an axial groove 41 in the axial direction of the female shaft 16B on the entire axial length of the teeth 51. A covering portion 61 that reduces the sliding resistance between them is coated.

  3 (1) and 3 (2) is preferably made of at least one of rubber, for example, natural rubber, synthetic rubber, or a mixture of natural rubber and synthetic rubber. . Further, the material of the covering portion 61 may be composed of at least one solid lubricant selected from molybdenum disulfide, graphite, and fluorine compounds.

  Furthermore, the material of the covering portion 61 is at least one of natural rubber, synthetic rubber, or a mixture of natural rubber and synthetic rubber, and at least one of molybdenum disulfide, graphite, and fluorine compounds. You may comprise with the material which contained the solid lubricant.

  The covering 61 is made of at least one polymer material selected from polytetrafluoroethylene, phenol resin, acetal resin, polyimide resin, polyamideimide resin, polyethersulfone resin, and polyphenylene sulfide resin. It is preferable.

  Furthermore, the material of the covering portion 61 is made of at least one polymer material selected from polytetrafluoroethylene, phenol resin, acetal resin, polyimide resin, polyamideimide resin, polyethersulfone resin, and polyphenylene sulfide resin. You may comprise with the material which contained the solid lubricant at least any one of molybdenum sulfide, a graphite, and a fluorine compound.

  After the covering portion 61 that reduces the sliding resistance with the groove 41 of the female shaft 16B is formed on the entire axial length of the teeth 51 of the male shaft 16A, the teeth 51 of the male shaft 16A are formed as shown in FIG. The groove 41 of the female shaft 16B is fitted over the entire length in the axial direction.

  Next, as shown in FIG. 4A, with the female shaft 16B fixed by a processing jig (not shown) or the like, a load (white arrow) in the direction perpendicular to the axis of the female shaft 16B is applied to the upper end of the male shaft 16A. (Lateral load) P shown in FIG. As a result, the male shaft 16A is bent relative to the female shaft 16B. The male shaft 16A may be fixed with a processing jig or the like, and a load in a direction perpendicular to the axis of the female shaft 16B may be applied to the lower end of the female shaft 16B.

  Therefore, reaction forces (black arrows) R1 and R2 act on the Q portion and R portion in the vicinity of both ends of the teeth 51 of the male shaft 16A, and the Q portion and R portion in the vicinity of both ends of the covering portion 61 in the axial direction. Is strongly compressed. The load P is preferably applied in a direction in which the side surfaces 511 and 511 of the teeth 51 of the male shaft 16A that transmits the rotational torque are strongly compressed, as indicated by the dashed-dotted ellipses T1, T2, T3, and T4 in FIG. .

  The load in the direction of bending the male shaft 16A relative to the female shaft 16B is not limited to an example in which the load is applied from one angular position in the circumferential direction of the male shaft 16A. That is, as shown in FIG. 4 (2), it is preferable to apply loads P1, P2, P3, and P4 from a plurality of angular positions in the circumferential direction of the male shaft 16A. Further, the number of times of applying the load is not limited to one time, and the load may be applied a plurality of times for one angular position.

  FIG. 6 shows a male shaft 16A having a telescopic shaft manufactured by the manufacturing method according to the first embodiment of the present invention. As shown in FIG. 6 (1), chamfered portions 62, 62 are formed in the vicinity of both axial ends of the covering portion 61 of the male shaft 16A. As shown in FIG. 6B, the chamfered portions 62, 62 are such that the gap δ between the groove 41 of the female shaft 16 </ b> B and the covering portion 61 increases toward the end of the covering portion 61 in the axial direction. Formed.

  Therefore, since there are no edges at both axial ends of the covering portion 61 of the male shaft 16A, a lubricant such as grease applied to the sliding surface between the groove 41 of the female shaft 16B and the covering portion 61 is The both ends of the covering portion 61 in the axial direction are not swept out of the sliding surface. Therefore, the lubricant is smoothly supplied to the sliding surface, the sliding resistance is kept small for a long time, and the life of the telescopic shaft is improved.

  Next, a second embodiment of the present invention will be described. FIG. 7 is an explanatory view showing a manufacturing process of the telescopic shaft according to the second embodiment of the present invention. In the following description, only structural portions and operations different from the above embodiment will be described, and redundant description will be omitted. Further, the same parts as those in the above embodiment will be described with the same numbers.

  The second embodiment is a modification of the first embodiment, and applies a load in a direction in which the male shaft 16A is bent relatively to the female shaft 16B, while the male shaft 16A is relatively axially aligned with the female shaft 16B. This is an example of sliding in the direction.

  That is, after forming the covering portion 61 that reduces the sliding resistance with the groove 41 of the female shaft 16B on the entire axial length of the teeth 51 of the male shaft 16A as in the first embodiment (see FIG. 3). The groove 41 of the female shaft 16B is fitted over the entire length of the teeth 51 of the male shaft 16A in the axial direction.

  Next, as shown in FIG. 7, with the female shaft 16B fixed by a processing jig or the like (not shown), a load in the direction perpendicular to the axis of the female shaft 16B (horizontal indicated by a white arrow) is applied to the upper end of the male shaft 16A. While applying the load (P), the male shaft 16A is slid in the axial direction (white arrow U direction) with respect to the female shaft 16B. As a result, the male shaft 16A is bent relative to the female shaft 16B while the male shaft 16A is slid relative to the female shaft 16B in the axial direction.

  The male shaft 16A is fixed with a processing jig or the like, and the female shaft 16B is slid in the axial direction with respect to the male shaft 16A while applying a load in a direction perpendicular to the axis of the female shaft 16B to the lower end of the female shaft 16B. You may let them.

  As a result, reaction forces (black arrows) R1 and R2 act on the Q portion and R portion in the vicinity of both ends of the teeth 51 of the male shaft 16A, and the Q portion and R in the vicinity of both ends of the covering portion 61 in the axial direction. The part is strongly compressed.

  The load in the direction of bending the male shaft 16A relative to the female shaft 16B is not limited to an example in which the load is applied from one angular position in the circumferential direction of the male shaft 16A, but the circumferential direction of the male shaft 16A. A load may be applied from a plurality of angular positions. Further, the number of times the load is applied is not limited to one time, and the load may be applied a plurality of times for one angular position.

  Also in the male shaft 16A of the telescopic shaft manufactured by the manufacturing method of the second embodiment of the present invention, the chamfered portions 62, 62 are provided in the vicinity of both ends in the axial direction of the covering portion 61 of the male shaft 16A, as in the first embodiment. It is formed. The chamfered portions 62 and 62 are formed such that a gap between the groove 41 of the female shaft 16 </ b> B and the covering portion 61 increases toward the end portion of the covering portion 61 in the axial direction.

  Accordingly, since both ends in the axial direction of the covering portion 61 of the male shaft 16A have no edge, the lubricant applied to the sliding surface between the groove 41 and the covering portion 61 of the female shaft 16B is not covered by the covering portion 61. The two end portions in the axial direction are not swept out of the sliding surface. Therefore, the lubricant is smoothly supplied to the sliding surface, the sliding resistance is kept small for a long time, and the life of the telescopic shaft is improved.

  Next, a third embodiment of the present invention will be described. FIG. 8 is an explanatory view showing a manufacturing process of the telescopic shaft according to the third embodiment of the present invention. In the following description, only structural portions and operations different from the above embodiment will be described, and redundant description will be omitted. Further, the same parts as those in the above embodiment will be described with the same numbers.

  The third embodiment is a modification of the first embodiment and is an example in which the covering portion 61 is heated while applying a load in a direction in which the male shaft 16A is relatively bent with respect to the female shaft 16B.

  That is, after forming the covering portion 61 that reduces the sliding resistance with the groove 41 of the female shaft 16B on the entire axial length of the teeth 51 of the male shaft 16A as in the first embodiment (see FIG. 3). The groove 41 of the female shaft 16B is fitted over the entire length of the teeth 51 of the male shaft 16A in the axial direction.

  Next, as shown in FIG. 8, the female shaft 16B is fixed with a processing jig or the like (not shown), and a heating device 71 such as a high-frequency coil is externally fitted to the outer periphery of the female shaft 16B. Subsequently, while applying a load P (lateral load indicated by a white arrow) P in a direction perpendicular to the axis of the female shaft 16B to the upper end of the male shaft 16A, the covering unit 61 is applied from the outer peripheral side of the female shaft 16B by the heating device 71. Heat. As a result, the male shaft 16A is bent relative to the female shaft 16B while heating the covering portion 61.

The male shaft 16A is fixed with a processing jig or the like, and the covering unit 61 is applied from the outer peripheral side of the female shaft 16B by the heating device 71 while applying a load in a direction perpendicular to the axis of the female shaft 16B to the lower end of the female shaft 16B. You may heat. The heating temperature of the covering portion 61 is preferably 30 degrees or more.
As another example, the covering portion 61 may be heated from the male shaft 16A side.

  As a result, reaction forces (black arrows) R1 and R2 act on the Q portion and R portion in the vicinity of both ends of the teeth 51 of the male shaft 16A, and the Q portion and R in the vicinity of both ends of the covering portion 61 in the axial direction. The part is strongly compressed.

  The load in the direction of bending the male shaft 16A relative to the female shaft 16B is not limited to an example in which the load is applied from one angular position in the circumferential direction of the male shaft 16A, but the circumferential direction of the male shaft 16A. A load may be applied from a plurality of angular positions. Further, the number of times the load is applied is not limited to one time, and the load may be applied a plurality of times for one angular position.

  Also in the male shaft 16A of the telescopic shaft manufactured by the manufacturing method of Example 3 of the present invention, as in Example 1, chamfered parts 62, 62 are provided in the vicinity of both ends in the axial direction of the covering part 61 of the male shaft 16A. It is formed. The chamfered portions 62 and 62 are formed such that a gap between the groove 41 of the female shaft 16 </ b> B and the covering portion 61 increases toward the end portion of the covering portion 61 in the axial direction. By heating the covering portion 61, the compressive load at which the covering portion 61 is plastically deformed is reduced, so that the chamfered portions 62 and 62 can be formed with a small load P.

  Accordingly, since both ends in the axial direction of the covering portion 61 of the male shaft 16A have no edge, the lubricant applied to the sliding surface between the groove 41 and the covering portion 61 of the female shaft 16B is not covered by the covering portion 61. The two end portions in the axial direction are not swept out of the sliding surface. Therefore, the lubricant is smoothly supplied to the sliding surface, the sliding resistance is kept small for a long time, and the life of the telescopic shaft is improved.

  Next, a fourth embodiment of the present invention will be described. FIG. 9 is an explanatory view showing the manufacturing process of the telescopic shaft according to the fourth embodiment of the present invention. In the following description, only structural portions and operations different from the above embodiment will be described, and redundant description will be omitted. Further, the same parts as those in the above embodiment will be described with the same numbers.

  The fourth embodiment is a modification of the first embodiment, and applies a load in a direction in which the male shaft 16A is relatively bent with respect to the female shaft 16B, while the male shaft 16A is relatively misaligned with respect to the female shaft 16B. This is an example of scrubbing exercise.

  That is, after forming the covering portion 61 that reduces the sliding resistance with the groove 41 of the female shaft 16B on the entire axial length of the teeth 51 of the male shaft 16A as in the first embodiment (see FIG. 3). The groove 41 of the female shaft 16B is fitted over the entire length of the teeth 51 of the male shaft 16A in the axial direction.

  Next, as shown in FIG. 9, with the female shaft 16B fixed by a processing jig or the like (not shown), a load in the direction perpendicular to the axis of the female shaft 16B (horizontal indicated by a white arrow) is applied to the upper end of the male shaft 16A. The male shaft 16A is rotated while applying the load (P). As a result, while the male shaft 16A is bent relative to the female shaft 16B, the male shaft 16A is caused to shave relative to the female shaft 16B (solid arrow V).

  The male shaft 16A is fixed by a processing jig or the like, and the female shaft 16B is rotated with respect to the male shaft 16A by rotating the female shaft 16B while applying a load in a direction perpendicular to the axis of the female shaft 16B to the lower end of the female shaft 16B. May be relatively slashed.

  As a result, reaction forces (black arrows) R1 and R2 act on the Q portion and R portion in the vicinity of both ends of the teeth 51 of the male shaft 16A, and the Q portion and R in the vicinity of both ends of the covering portion 61 in the axial direction. The part is strongly compressed.

  The load in the direction of bending the male shaft 16A relative to the female shaft 16B is not limited to an example in which the load is applied from one angular position in the circumferential direction of the male shaft 16A, but the circumferential direction of the male shaft 16A. A load may be applied from a plurality of angular positions. Further, the number of times the load is applied is not limited to one time, and the load may be applied a plurality of times for one angular position.

  Also in the male shaft 16A of the telescopic shaft manufactured by the manufacturing method of Example 4 of the present invention, as in Example 1, chamfered portions 62, 62 are provided in the vicinity of both ends in the axial direction of the covering portion 61 of the male shaft 16A. It is formed. The chamfered portions 62 and 62 are formed such that a gap between the groove 41 of the female shaft 16 </ b> B and the covering portion 61 increases toward the end portion of the covering portion 61 in the axial direction.

  Accordingly, since both ends in the axial direction of the covering portion 61 of the male shaft 16A have no edge, the lubricant applied to the sliding surface between the groove 41 and the covering portion 61 of the female shaft 16B is not covered by the covering portion 61. The two end portions in the axial direction are not swept out of the sliding surface. Therefore, the lubricant is smoothly supplied to the sliding surface, the sliding resistance is kept small for a long time, and the life of the telescopic shaft is improved.

  Next, a fifth embodiment of the present invention will be described. FIG. 10 is an explanatory view showing the manufacturing process of the telescopic shaft according to the fifth embodiment of the present invention. In the following description, only structural portions and operations different from the above embodiment will be described, and redundant description will be omitted. Further, the same parts as those in the above embodiment will be described with the same numbers.

  The fifth embodiment is a modification of the first embodiment. The step of applying a load in the direction of bending the male shaft 16A relative to the female shaft 16B, and the male shaft 16A relatively to the female shaft 16B are provided. This is an example in which the step of sliding in the axial direction is sequentially performed.

  That is, after forming the covering portion 61 that reduces the sliding resistance with the groove 41 of the female shaft 16B on the entire axial length of the teeth 51 of the male shaft 16A as in the first embodiment (see FIG. 3). The groove 41 of the female shaft 16B is fitted over the entire length of the teeth 51 of the male shaft 16A in the axial direction.

  Next, as shown in FIG. 10A, with the female shaft 16B fixed by a processing jig (not shown) or the like, a load (white arrow) in the direction perpendicular to the axis of the female shaft 16B is applied to the upper end of the male shaft 16A. (Lateral load) P shown in FIG. As a result, the male shaft 16A is bent relative to the female shaft 16B.

  The male shaft 16A may be fixed with a processing jig or the like, and a load in a direction perpendicular to the axis of the female shaft 16B may be applied to the lower end of the female shaft 16B. As a result, reaction forces (black arrows) R1 and R2 act on the Q portion and R portion in the vicinity of both ends of the teeth 51 of the male shaft 16A, and the Q portion and R in the vicinity of both ends of the covering portion 61 in the axial direction. The part is strongly compressed.

  The load in the direction of bending the male shaft 16A relative to the female shaft 16B is not limited to an example in which the load is applied from one angular position in the circumferential direction of the male shaft 16A, but the circumferential direction of the male shaft 16A. A load may be applied from a plurality of angular positions. Further, the number of times the load is applied is not limited to one time, and the load may be applied a plurality of times for one angular position.

  Next, as shown in FIG. 10B, the male shaft 16A is slid relative to the female shaft 16B in the axial direction (in the direction of the white arrow W). Thereafter, as shown in FIG. 10 (3), a load (lateral load indicated by a white arrow) P in the direction orthogonal to the axis of the female shaft 16B is again applied to the upper end of the male shaft 16A. As a result, the male shaft 16A is again bent relative to the female shaft 16B. This bending, relative axial sliding, and bending may be repeated a plurality of times.

  In the telescopic male shaft 16A manufactured by the manufacturing method according to the fifth embodiment of the present invention, as in the first embodiment, chamfered portions 62 and 62 are provided in the vicinity of both ends in the axial direction of the covering portion 61 of the male shaft 16A. It is formed. The chamfered portions 62 and 62 are formed such that a gap between the groove 41 of the female shaft 16 </ b> B and the covering portion 61 increases toward the end portion of the covering portion 61 in the axial direction.

  Accordingly, since both ends in the axial direction of the covering portion 61 of the male shaft 16A have no edge, the lubricant applied to the sliding surface between the groove 41 and the covering portion 61 of the female shaft 16B is not covered by the covering portion 61. The two end portions in the axial direction are not swept out of the sliding surface. Therefore, the lubricant is smoothly supplied to the sliding surface, the sliding resistance is kept small for a long time, and the life of the telescopic shaft is improved.

  In the above embodiment, the covering portion 61 for reducing the sliding resistance is formed on the tooth 51 side of the male shaft 16A, but the covering portion 61 for reducing the sliding resistance is formed on the groove 41 side of the female shaft 16B. Also good. Moreover, you may form the coating | coated part 61 which reduces sliding resistance in both the tooth | gear 51 of the male shaft 16A, and the groove | channel 41 of the female shaft 16B. Furthermore, you may shape | mold the male shaft 16A or the whole female shaft 16B with the same material as the coating | coated part 61 which reduces sliding resistance.

  Moreover, although the said Example demonstrated the example which applied this invention to the intermediate shaft 16, it can apply to the arbitrary expansion-contraction shafts which comprise a steering apparatus, such as the steering shaft 12. FIG.

BRIEF DESCRIPTION OF THE DRAWINGS The steering apparatus which has the expansion-contraction shaft of this invention is shown whole, it is the side view which cut | disconnected one part, Comprising: The Example applied to the electric power steering apparatus which has a steering assistance part is shown. It is a longitudinal cross-sectional view which shows the principal part of the expansion-contraction shaft of Example 1 of this invention. 2 is an enlarged cross-sectional view taken along the line AA of FIG. 2, (1) is an enlarged cross-sectional view showing a telescopic shaft covering a sleeve, and (2) is an enlarged cross-sectional view showing a telescopic shaft coated with a covering portion. It is explanatory drawing which shows the manufacturing process of the expansion-contraction shaft of Example 1 of this invention, Comprising: (1) is a longitudinal cross-sectional view of the principal part of an expansion-contraction shaft, (2) is a top view of (1). It is a perspective view which shows the male shaft of the expansion-contraction shaft of Example 1 of this invention. The male shaft of the expansion-contraction shaft manufactured with the manufacturing method of Example 1 of this invention is shown, (1) is a longitudinal cross-sectional view of a male shaft single-piece | unit, (2) is the S section expanded sectional view of (1). It is explanatory drawing which shows the manufacturing process of the expansion-contraction shaft of Example 2 of this invention. It is explanatory drawing which shows the manufacturing process of the expansion-contraction shaft of Example 3 of this invention. It is explanatory drawing which shows the manufacturing process of the expansion-contraction shaft of Example 4 of this invention. It is explanatory drawing which shows the manufacturing process of the expansion-contraction shaft of Example 5 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Steering wheel 12 Steering shaft 12A Female shaft 12B Male shaft 13 Steering column 13A Outer column 13B Inner column 14 Support bracket 15 Universal joint 16 Intermediate shaft 16A Male intermediate shaft (male shaft)
16B Female intermediate shaft (Female shaft)
DESCRIPTION OF SYMBOLS 17 Universal joint 18 Car body 20 Assist device 21 Gear housing 23 Output shaft 26 Electric motor 261 Case 30 Steering gear 31 Input shaft 32 Tie rod 41 Groove 51 Tooth 511 Side surface 61 Covering portion 62 Chamfered portion 71 Heating device

Claims (10)

A male shaft having a non-circular outer peripheral shape,
A female shaft having a non-circular inner peripheral shape that is fitted on the outer periphery of the male shaft so as to be slidable in the axial direction and capable of transmitting rotational torque;
A method for producing a telescopic shaft, which is formed over the entire axial length of the non-circular outer periphery of the male shaft and has a covering portion that reduces sliding resistance between the inner periphery of the female shaft,
Forming a covering portion for reducing a sliding resistance between the inner circumference of the female shaft on the entire axial length of the non-circular outer circumference of the male shaft;
A step of fitting the non-circular inner periphery of the female shaft to the entire axial length of the non-circular outer periphery of the male shaft forming the covering portion;
A step of applying a load in a direction of bending the male shaft relative to the female shaft, and compressing the covering portions in the vicinity of both axial ends of the non-circular outer periphery of the male shaft to form a chamfered portion. A method for producing a telescopic shaft characterized by the above. In the manufacturing method of the expansion-contraction shaft described in Claim 1,
A method for manufacturing a telescopic shaft, wherein the covering portion is heated while applying a load in a direction of bending the male shaft relative to the female shaft. In the manufacturing method of the expansion-contraction shaft described in Claim 2,
A method for producing a telescopic shaft, wherein the covering portion is heated to 30 degrees or more. In the manufacturing method of the expansion-contraction shaft described in Claim 1,
A method for manufacturing an extendable shaft, wherein the male shaft is slid relative to the female shaft in the axial direction while applying a load in a direction of bending the male shaft relative to the female shaft. In the manufacturing method of the expansion-contraction shaft described in Claim 1,
A method for manufacturing a telescopic shaft, wherein the male shaft is relatively razor-moved relative to the female shaft while applying a load in a direction in which the male shaft is bent relative to the female shaft. In the manufacturing method of the expansion-contraction shaft described in Claim 1,
A method for producing a telescopic shaft, wherein a load in a direction of bending the male shaft relative to the female shaft is applied from a plurality of angular positions in a circumferential direction of the male shaft. In the manufacturing method of the expansion-contraction shaft described in Claim 1,
The expansion and contraction characterized by sequentially performing a step of applying a load in a direction of bending the male shaft relative to the female shaft and a step of sliding the male shaft relative to the female shaft in the axial direction. Shaft manufacturing method. In the manufacturing method of the expansion-contraction shaft as described in any one of Claim 1- Claim 7,
The method for manufacturing a telescopic shaft, wherein the covering portion is made of at least one of rubber, polymer material, and solid lubricant.   A telescopic shaft manufactured by the method for manufacturing the telescopic shaft according to any one of claims 1 to 8. A male shaft having a non-circular outer peripheral shape,
A female shaft having a non-circular inner peripheral shape that is fitted on the outer periphery of the male shaft so as to be slidable in the axial direction and capable of transmitting rotational torque;
A telescopic shaft that is formed over the entire axial length of the noncircular inner periphery of the female shaft and has a covering portion that reduces sliding resistance with the outer periphery of the male shaft,
Forming a covering portion for reducing the sliding resistance between the outer circumference of the male shaft on the entire axial length of the noncircular inner circumference of the female shaft;
A step of externally fitting the entire axial length of the non-circular inner periphery of the female shaft in which the covering portion is formed on the non-circular outer periphery of the male shaft;
Manufactured by applying a load in the direction of bending the male shaft relative to the female shaft and compressing the covering portions in the vicinity of both axial ends of the noncircular inner periphery of the female shaft to form a chamfered portion Telescopic shaft.

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