JP2012154414A - Shell type needle bearing and joint cross type universal joint, and radial rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure, with which both cost reduction and secured durability can be achieved.SOLUTION: The whole outer face of a shell type outer ring 9 is covered with a chemical conversion coating such as an iron phosphate coating having corrosion resistance. The chemical conversion coating is exposed from the outer face of the shell type outer ring 9 at its portion internally fitted to a circular hole 6a of a yoke 2a to abut on the inner peripheral face of the circular hole 6a. A portion deviating from the circular hole 6a, with which the tips of seal lips 17, 18 constituting a seal ring 14 may have slide contact, is covered with a coating 21 to sufficiently improve its corrosion resistance. Without the need for manufacturing the shell type outer ring 9 of an expensive stainless steel plate, there is no event that the surface roughness of the portion is degraded by rust. The tips of the seal lips 17, 18 are preventive of sealing performance deterioration due to wear.

Description

  The present invention has a shell-type outer ring formed by bending a metal plate into a bottomed cylindrical shape, and a gap between the opening end of the outer ring and the outer peripheral surface of a shaft inserted on the inner diameter side of the outer ring The present invention relates to a shell-type needle bearing that is used in a state in which is sealed with a seal ring, and an improvement in a cross-shaft universal joint incorporating such a shell-type needle bearing.

  For example, a cross-shaft universal joint is incorporated at the joint between the end of the drive shaft that constitutes the drive system of an automobile and another rotary shaft, and the drive shaft and the rotary shaft are arranged non-linearly. The rotational force can be transmitted freely. Alternatively, a cross shaft type universal joint is incorporated between the steering shaft and the intermediate shaft constituting the automobile steering device, between the intermediate shaft and the pinion shaft of the steering gear unit, and arranged on a non-linear line. Rotational force can be transmitted between these shafts. The structure of a cross shaft type universal joint used for such a part has been widely known as described in, for example, Patent Documents 1-6.

  FIG. 4 shows an example of a cruciform universal joint that has been widely known. The universal joint 1 is formed by coupling a pair of yokes 2a and 2b and a cross shaft 3 via four shell needle bearings 4 and 4 so as to be relatively displaceable. Each of the yokes 2a and 2b has a bifurcated shape with a pair of arm portions 5a and 5b, and circular holes 6a and 6b are formed at the tips of the arm portions 5a and 5b, respectively. Yes. The circular holes 6a, 6a (6b) formed at the tip of the same yoke 2a (2b) are concentric with each other. The cross shaft 3 is formed by fixing four shaft portions 8 and 8 radially (at equal intervals in the circumferential direction) to the outer peripheral surface of the coupling base portion 7. The yokes 2a and 2b constituting the universal joint 1 support the shafts 8 and 8 in the circular holes 6a and 6b so as to be swingably displaceable by the shell type needle bearings 4 and 4, respectively. Thus, the oscillating displacement and the torque transmission are freely coupled via the cross shaft 3.

  Each of the shell type needle bearings 4, 4 includes a single shell type outer ring 9 and a plurality of needles 10, 10. The shell type outer ring 9 is formed by bending a hard metal plate such as a carbon steel plate by plastic working such as deep drawing, and includes a cylindrical portion 11, a bottom plate portion 12, and an inward flange portion 13. Prepare. Of these, the bottom plate portion 12 closes the entire axial end of the cylindrical portion 11 (on the outer surface side of the arm portions 5a and 5b in the assembled state in the circular holes 6a and 6b). The inward flange 13 is radially inward from the other axial end of the cylindrical portion 11 (the inner side of the arms 5a and 5b in the assembled state in the circular holes 6a and 6b). The surface facing the needles 10 and 10 is curved in a direction that becomes a concave surface.

  Each of the shell type needle bearings 4, 4, each having the above-described configuration, has the shell type outer rings 9, 9 fitted into the circular holes 6 a, 6 b by internal fitting and fixed, and each needle 10 and 10 are assembled in a state where the shaft portions 8 and 8 of the cross shaft 3 are inserted. In this assembly operation, the shell type needle roller bearings 4 and 4 are inserted into the circular holes 6a and 6b in a state where the shafts 8 and 8 are inserted into the circular holes 6a and 6b. This is performed by press-fitting from the outer surface side openings of the arms 5a and 5b. In addition, seal rings 14 and 14 are preliminarily fitted and supported on the base end portions of the shaft portions 8 and 8 by interference fitting. In the state after the assembly is completed, the inner peripheral surface of the cylindrical portion 11 of each shell type outer ring 9, 9 functions as an outer ring raceway, and the outer peripheral surface of each shaft portion 8, 8 functions as an inner ring raceway.

  Each of the seal rings 14, 14 is formed by reinforcing an elastic material 16 with a cored bar 15. Among these, the elastic member 16 includes a radial seal lip 17 and a thrust seal lip 18. In a state where the cross shaft 3 and each shell type outer ring 9, 9 are combined to form the universal joint 1, the distal end edge of the radial seal lip 17 is within the outer peripheral surface of each shell type outer ring 9, 9. It abuts elastically at the end near the opening over the entire circumference. Further, the leading edge of the thrust seal lip 18 is in elastic contact with the outer surfaces of the inward flange portions 13 and 13 over the entire circumference. In this state, the seal rings 14, 14 block the internal space and the external space of the shell type outer rings 9, 9, and lubricant such as grease sealed inside the shell type outer rings 9, 9. Is prevented from leaking to the outside, and foreign matter is prevented from entering the inside of the shell-type outer rings 9, 9 from the outside.

  When the universal joint 1 as described above is used in a state where it is assembled to, for example, a connecting portion between the end portion of the drive shaft and another rotating shaft, from the aspect of achieving both low cost and ensuring durability, There is room for improvement in this respect. First, in order to reduce the cost, carbon steel sheets (skin-hardened steel, bearing steel, etc.) that can keep procurement costs low as the metal plates constituting the shell-type outer rings 9, 9 incorporated in the shell-type needle bearings 4, 4 described above. Are preferably used). However, in the case of a carbon steel plate, it is inevitable that the surface is corroded if the use conditions become severe. For example, when the universal joint 1 is incorporated in a drive system of an automobile, a corrosive substance such as muddy water rolled up during running or water mixed with a snow melting agent adheres to the surface of the shell type outer rings 9 and 9. Then, rust is generated on this surface.

  The surface portions of the shell-type outer rings 9 and 9 where rust is generated have a large roughness (a rough surface having a large friction coefficient), and the tips of the seal lips 17 and 18 constituting the seal rings 14 and 14. These seal lips 17 and 18 wear out in strong friction with the edges. For example, in the initial stage, as shown in FIG. 5A, the tip edges of the seal lips 17 and 18 are in contact with the surface of the shell-type outer ring 9 without any gaps over the entire circumference. Even if the rust 19 is generated on a part of the surface of the shell type outer ring 9 as shown in FIG. 5B, the leading edge of the radial seal lip 17 is first caused by friction with the rust 19. Parts wear out. As a result, a gap 20 is formed between the distal end edge of the radial seal lip 17 and the surface of the shell-type outer ring 9. As a result, the corrosive substance enters deeper than the radial seal lip 17 through the gap 20, and as shown in FIG. 19a occurs. Due to the friction with the rust 19a, the tip edge portion of the thrust seal lip 18 is worn, and a gap 20a is also formed between the tip edge of the thrust seal lip 18 and the surface of the shell type outer ring 9. As a result, the sealing function by the respective seal lips 17 and 18 is reduced or lost, and it becomes impossible to prevent the leakage of the lubricant and the invasion of foreign matter.

  As described in Patent Document 5, the surface of the universal joint after assembly may be coated for rust prevention including the surface of the shell type needle bearing. However, in this case, as described in the above-mentioned Patent Document 5, not only is there concern about deterioration of the sealing performance due to the presence of the stepped surface of the coating film, but there is a relative displacement between the seal ring and the shell type outer ring. Thus, the corrosive substance adheres to the surface of the shell-type outer ring that is not covered with the coating film, and the possibility that the corrosion proceeds from this portion remains. If the entire outer surface of the shell type outer ring is painted prior to assembly to the yoke, the above-mentioned problems can be solved, but the outer diameter of the shell type outer ring is increased by the amount of the coating film. This not only hinders the work of press-fitting into the circular hole on the yoke side, but also deteriorates the dimensional accuracy after press-fitting.

  If the shell type outer ring 9 is made of a stainless steel plate, the occurrence of rust 19 and 19a as described above can be suppressed, and the durability of the universal joint 1 incorporating the shell type needle bearings 4 and 4 can be achieved. However, a stainless steel plate is not only more expensive than a carbon steel plate, but it is also troublesome to draw a material having the required hardness, which makes the processing itself difficult and increases the processing cost. For this reason, it is desirable to avoid the use of stainless steel sheets in view of cost reduction.

  Patent Documents 7 and 8 describe the prevention of insoluble metal phosphate-treated film (in the case of Patent Document 7), phosphate-treated film (in the case of Patent Document 8), etc. on the surface of a rolling bearing component such as an outer ring. The formation of a chemical conversion coating for rust is described. These chemical conversion treatment coatings do not require the outer diameter of the outer ring to be substantially increased, and a certain degree of antirust effect can be expected. And, for example, it is possible to prevent the formation of through holes in the shell-type outer ring or the occurrence of corrosion that causes a significant decrease in strength during the period of use required for the universal joint. However, when the use conditions become severe, there is a possibility that thin rust will be generated on the surface. The wear of the tip edge of the seal lip as described above proceeds even by such thin rust. For this reason, even if the usage conditions are severe, it is not always sufficient to maintain the sealing performance of the seal ring for a long period of time and to ensure the durability of the universal joint incorporating the shell type needle bearing. .

Japanese Patent Application Laid-Open No. 8-135684 Japanese Patent Laid-Open No. 9-60650 JP 2005-48809 A JP 2006-29551 A JP 2010-1810115 A JP 2010-181016 A JP 2002-146837 A JP 2002-294465 A

  In view of the circumstances as described above, the present invention has been invented to realize a structure of a shell type needle bearing and a cross shaft type universal joint capable of achieving both low cost and ensuring durability.

Among the shell-type needle bearing and the cross shaft type universal joint of the present invention, the invention of the shell-type needle bearing according to claim 1 is similar to the shell-type needle bearing that has been widely known as described above. A shell type outer ring and a plurality of needles are provided.
In particular, in the shell type needle bearing of the present invention, the entire outer surface of the shell type outer ring has a certain degree of corrosion resistance and improves the bonding strength between the shell type outer ring and the coating film described below. It is covered with a chemical conversion coating. And the said chemical conversion treatment film is exposed in the outer surface of this shell type outer ring | wheel in the part which is fitted by the circular hole formed in the outer side member in use condition, and contact | abuts with the internal peripheral surface of this circular hole. Furthermore, at least a part of the part removed from the circular hole is covered with a coating film for improving the corrosion resistance.

  The portion of the outer surface of the shell-type outer ring that is covered with the coating film is the portion closer to the other end in the axial direction (closer to the opening) of the outer surface as in the invention described in claim 2. And a bottom plate portion formed on one end side of the shell-type outer ring existing inside the circular hole as in the invention described in claim 3. One or both of the outer surfaces.

Further, the invention of the cross shaft type universal joint described in claim 4 is similar to the cross shaft type universal joint that has been widely known as described above, and a pair of yokes and a total of four circles. A hole, a cross shaft, and four shell type needle bearings are provided. Each of these shell type needle bearings is a shell type needle bearing as described above.
In the case of carrying out the present invention relating to such a cross shaft universal joint, it is preferable that four seal rings each including a radial seal lip and a thrust seal lip are provided as in the invention described in claim 5. Shall be. And the other end part of the axial direction of the outer peripheral surface of the cylindrical part of each shell type outer ring | wheel and the outer surface of the said inward flange part are covered with the said continuous coating film.

As described above, in the case of the shell type needle bearing and the cross shaft type universal joint of the present invention, only the chemical conversion treatment film is provided in the portion of the outer peripheral surface of the shell type outer ring that is fitted into the circular hole of the outer member. Even if a coating film is present, the amount is small. The chemical conversion coating film is extremely thin and hardly increases the outer diameter of the shell-type outer ring. For this reason, this shell-type outer ring can be fitted and fixed to the circular hole without interference, and part of the coating can be scraped off due to internal fitting work, There is almost no. In addition to the chemical conversion coating, the parts that require a high degree of corrosion resistance, such as the part where the tip edge of the seal lip slides, are covered with the coating film as well. Can be prevented. Therefore, it is possible to prevent the tip edge of the seal lip from being worn due to friction with the surface of the shell type outer ring, which has become rough due to rust (corrosion product).
In this way, according to the present invention, it is possible to realize the structure of a shell type needle bearing and a cross shaft type universal joint that can achieve both low cost and durability.

FIG. 3 is a cross-sectional view of a main part showing a first example of an embodiment of the present invention. The principal part sectional view showing the 2nd example. The principal part sectional view showing the 3rd example. The partial cutting side view which shows the universal joint incorporating the shell type needle bearing used as the object of this invention in the state which abbreviate | omitted one part. The principal part sectional drawing which shows the condition where the front-end | tip part of the seal lip which comprises a seal ring wears with corrosion of the outer surface of a shell type outer ring | wheel according to the order of progress.

[First example of embodiment]
FIG. 1 shows a first example of an embodiment of the present invention corresponding to claims 1, 2, 4, and 5. The feature of the present invention including this example is that the shell type needle bearing and the cross shaft type universal joint that can achieve both low cost and durability can be realized on the surface of the shell type outer ring 9 in order to realize the structure. The point is to devise a coating for this. Since the configuration and operation of the other parts are the same as those of the above-described conventional structure, the illustration and description of the equivalent parts are omitted or simplified, and the following description will focus on the characteristic parts of the present invention.

  The outer surface of the shell-type outer ring 9, that is, the outer surface of the bottom plate portion 12 and the inward flange portion 13 (side surfaces opposite to each other) and the entire outer peripheral surface of the cylindrical portion 11 is an iron phosphate that is a chemical conversion treatment film having corrosion resistance. It is covered with a film. The method for forming this iron phosphate coating is not particularly limited. A general treatment method such as application of a commercially available iron phosphate-based surface treatment agent by spraying or immersion in the surface treatment agent can be used. If such a base treatment is applied to the outer surface of the shell type outer ring 9, the outer surface of the shell type outer ring 7 can be degreased, and at the same time, a chemical conversion treatment film (iron phosphate film) can be formed on the outer surface.

  Further, a coating film 21 covers a portion indicated by a broken line α in FIG. That is, among the outer peripheral surfaces of the cylindrical portion 11 constituting the shell type outer ring 9, the opening-side end portion (the end portion on the opposite side to the bottom plate portion 12) and the outer side surface of the inward flange portion 13 provided at the opening peripheral edge portion. In addition, the coating film 21 is formed. The type of coating material constituting the coating film 21 has good adhesion to the steel plate constituting the shell-type outer ring 7, is easy to form a coating film, has sufficient corrosion resistance, and There is no particular limitation as long as the surface can be made smooth. For example, an epoxy resin paint can be preferably used.

  The coating film 21 is formed in the radial and thrust seal lips 17 and 18 constituting the seal ring 14 based on the torque applied between the yoke 2a (2b) and the cross shaft 3 when the universal joint is used. The part where the tip edge of the slidable part may come into sliding contact is completely included, and a part slightly wider than this part. That is, when the torque increases, the amount of elastic deformation of the yoke 2a (2b), the cross shaft 3, etc. increases, and the leading edges of the seal lips 17 and 18 deviate from the positions shown in FIG. However, the width of the coating film 21 is sufficiently wide so that the respective leading edges do not come off the coating film 21. Specifically, the inner diameter side end of the coating film 21 on the other end side in the axial direction is present at a position reaching the inner peripheral edge of the inward flange 13. Further, the outer end of the coating film 21 in the axial direction is located at a position where it slightly enters (for example, 0.5 mm to 1 mm) inside the circular hole 6a (6b). That is, the amount of protrusion of the shell-type outer ring 9 from the inner surface of the arm portion 5a (5b) of the yoke 2a (2b) excluding the tip is H, and the end surface (inward flange 13) of the shell-type outer ring 9 W−H = 0.5 mm to 1 mm, where W is the distance from the outer surface of the coating film 21 to the outer end of the coating film 21 in the axial direction (the axial width of the coating film 21). In addition, in order to form the coating film 21 only in the above-mentioned range, in addition to masking the axially intermediate portion of the bottom plate portion 12 to the cylindrical portion 11 with a cover or tape, A spraying operation for forming the coating film 21 is performed in a state of being covered with a cap.

  As described above, according to the structure of the present example, it is possible to achieve both reduction in cost and securing of durability of the shell type needle bearing 4 and the cross shaft type universal joint incorporating the shell type needle bearing 4. That is, in the case of the structure of this example, it is fitted into the circular hole 6a (6b) of the yoke 2a (2b) by an interference fit in the outer peripheral surface of the cylindrical portion 11 constituting the shell type outer ring 9. For the most part, only the chemical conversion coating is present. The film of the chemical conversion coating is extremely thin, and the outer diameter of the shell-type outer ring 9 is hardly increased. A part of the coating film 21 (a part in the circumferential direction of a part having a width of 0.5 mm to 1 mm) is fitted in the circular hole 6a (6b), but the part is suppressed slightly. It is done. Even in this portion, the cylindrical portion 11 is merely pushed into the circular hole 6a (6b) at the final stage of the work of fitting the cylindrical portion 11 into the circular hole 6a (6b). Moreover, in the case of this example, the thickness of the coating film 21 is suppressed to about 0.005 mm to 0.015 mm, although it is larger than the thickness of the chemical conversion treatment film. For this reason, the presence of the coating film 21 hardly interferes with the fitting operation, and the coating film 21 is hardly scraped off with the fitting operation.

  When the assembly of the cross shaft universal joint is completed, the leading edge of each of the radial and thrust seal lips 17 and 18 constituting the seal ring 14 is the surface of the coating film 21, and the width of the coating film 21. The slidable contact is sufficiently made from the both end edges in the direction toward the center side of the coating film 21. The surface of the coating film 21 is a smooth surface and has sufficiently excellent corrosion resistance. For this reason, even when used over a long period of time in a harsh corrosive environment, the surface of the portion where the tip edges of the seal lips 17 and 18 are in sliding contact does not become rough. That is, unlike the above-described conventional structure, the tip edge of the seal lip does not wear due to friction with the surface of the shell-type outer ring roughened by rust (corrosion product).

[Second Example of Embodiment]
FIG. 2 shows a second example of an embodiment of the present invention corresponding to claims 1 and 3 to 5. In the case of this example, the coating film 21a is formed on the outer surface of the bottom plate portion 12 indicated by the broken line β in FIG. Since the bottom plate portion 12 exists inside the circular hole 6a (6b) formed in the yoke 2a (2b) and is located in a slightly recessed portion from the outer surface of the yoke 2a (2b), the circular hole 6a (6b) ) And corrosive substances such as muddy water containing snow melting salt are likely to accumulate in the portion surrounded by the inner peripheral surface and the bottom plate portion 12, and the corrosive environment becomes very severe. In general, if a chemical conversion treatment film having corrosion resistance is formed on the outer surface of the shell-type outer ring 9, the bottom plate portion 12 is corroded to the extent that it leads to the generation of through holes and a decrease in strength. There is nothing. However, if the coating film 21a similar to the coating film 21 of the first example of the above-described embodiment is formed on the bottom plate portion 12 as in the structure of this example, the durability of the bottom plate portion 12 is further increased. Can be improved.

[Third example of embodiment]
FIG. 3 shows a third example of the embodiment of the invention corresponding to claims 1 to 5. In the case of this example, the coating film 21 is applied to the outer surface of the cylindrical portion 11 constituting the shell-type outer ring 9 on the outer surface of the opening-side end portion and the inward flange portion 13, and the coating film is applied to the outer surface of the bottom plate portion 12. 21a is formed. For this reason, the operation / effect of the first example of the embodiment described above and the operation / effect of the second example of the embodiment described above can be obtained together.

  As in the present invention, in order to give a certain degree of corrosion resistance to the entire surface of the bearing ring of the rolling bearing, a chemical conversion treatment film is formed on the entire surface, and in particular, it is necessary to have a high degree of corrosion resistance. Only the rolling bearings other than the shell-type needle bearing can be applied to the technique for forming the coating film only (the invention described in claim 6). That is, the entire surface of a bearing ring (outer ring or inner ring) for a radial bearing formed by subjecting a bearing steel material to forging, cutting, and grinding is covered with a chemical conversion coating, and sealed with a part of the bearing ring. The effect | action and effect of this invention can be acquired by covering only the part which the front-end edge of a lip slidably contacts with a coating film.

DESCRIPTION OF SYMBOLS 1 Universal joint 2a, 2b Yoke 3 Cross shaft 4 Shell type needle bearing 5a, 5b Arm part 6a, 6b Circular hole 7 Connection base part 8 Shaft part 9 Shell type outer ring 10 Needle 11 Cylindrical part 12 Bottom plate part 13 Inward flange part 14 Seal ring 15 Core 16 Elastic material 17 Radial seal lip 18 Thrust seal lip 19, 19a Rust 20, 20a Clearance 21, 21a Coating film

Claims (6)

A shell-type outer ring formed by bending a metal plate and fitted and fixed in a circular hole formed in the outer member in use, and a plurality of needles provided to roll on the inner diameter side of the shell-type outer ring, With
Of these, the shell-type outer ring includes a cylindrical portion, a bottom plate portion that covers the whole axial one end side of the cylindrical portion, and an inward flange portion that is bent radially inward from the other axial end side of the cylindrical portion. Shell type needle bearing
The entire outer surface of the shell-type outer ring is covered with a chemical conversion coating having corrosion resistance, and the outer surface of the shell-type outer ring is fitted into the circular hole and comes into contact with the inner peripheral surface of the circular hole. The shell-type needle is characterized in that the chemical conversion coating is exposed at a portion, and at least a part of the portion removed from the circular hole is covered with a coating for improving corrosion resistance bearing.   The tip edge of the seal lip constituting the seal ring that is externally fitted and fixed to the outer peripheral surface of the shaft portion inserted on the inner diameter side of each needle is in sliding contact with the portion near the other axial end of the outer surface of the shell type outer ring. The shell type needle bearing according to claim 1, wherein a possible portion is covered with the coating film.   The shell type needle bearing according to any one of claims 1 to 2, wherein the bottom plate portion is present inside the circular hole, and an outer surface of the bottom plate portion is covered with the coating film. .   A pair of yokes each formed in a bifurcated shape, a pair of each yoke formed concentrically at both ends of each of the yokes, a total of four circular holes, and an outer peripheral surface of the coupling base The four shafts are radially fixed to each other, the cross shafts combined with the two yokes in a state where the shafts are inserted into the circular holes, the outer peripheral surfaces of the shafts, and the 4. A cross shaft type universal joint provided with four shell type needle bearings respectively provided between the inner peripheral surfaces of the respective circular holes, wherein each of these shell type needle bearings is defined in claims 1 to 3. A cross shaft type universal joint, which is the shell type needle bearing described in any one of the items.   Four seal rings provided between the base end portions of the shaft portions and the openings of the shell-type outer rings in a state where the base portions are fitted and supported on the base end portions of the shaft portions. Each of these seal rings includes a radial seal lip that is in contact with the outer peripheral surface of the other end in the axial direction protruding from the circular hole, of the outer surface of each shell-type outer ring, and the shell-type outer ring. A thrust seal lip that is in contact with the outer surface of the inward flange portion over the entire circumference, and the other axial end portion of the outer peripheral surface of the cylindrical portion of each shell-type outer ring and the outer surface of the inward flange portion; Are covered with the coating films which are continuous with each other, the cross shaft type universal joint according to claim 4.   Radial rolling bearing comprising an outer ring having an outer ring raceway on the inner peripheral surface, an inner ring having an inner ring raceway on the outer peripheral surface, and a plurality of rolling elements provided between the outer ring raceway and the inner ring raceway so as to roll freely. In this case, the entire outer surface of the bearing ring which is at least one of the outer ring and the inner ring is covered with a chemical conversion coating having corrosion resistance, and at least a part of the outer surface of the bearing ring is Radial rolling bearing, characterized by being covered with a coating to improve corrosion resistance.

Images