GB2136078A

GB2136078A - Axial Securing Element

Info

Publication number: GB2136078A
Application number: GB08317381A
Authority: GB
Inventors: Walter Bauer
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-06-26
Filing date: 1983-06-27
Publication date: 1984-09-12
Also published as: FR2529272B1; DE3223994A1; FR2529272A1; IT1169737B; GB2136078B; DE3223994C2; JPS5926612A; GB8317381D0; IT8321782A0

Abstract

A axial securing element 3 for fixing two workplaces in relation to each other consists of a ring 3 of rectangular cross- section having conical external surfaces set obliquely at an angle of less than 90 DEG to the engaging surfaces on the work pieces and designed to change their diameter so that they can be fitted into notches on the work pieces 1, 2 as shown in fig. 8. To enable them to take up exceptionally high axial forces, the ring is made up of at least two part-elements 3a, b, c (fig. 2) or 3d, 3e (fig. 8) which can be placed into position independently of each other but cooperate with each other. These part-elements may consist of ring segments (fig. 2) obtained by sub-dividing a ring at its circumference or they may consist of split part-rings of different mean diameters (fig. 8), with the internal and external contours so adjusted to each other that the part-rings fit into each other with the surfaces facing each other. <IMAGE>

Description

SPECIFICATION Axial Securing Element This invention relates to an axial securing element for fixing together two work pieces having internal and, respectively, external cylindrical engaging surfaces, consisting of split ring elements of rectangular cross section having conical external surfaces extending obliquely to the engaging surfaces at an angle of less than 900 and capable of being inserted into notches of the work pieces by an elastic change in their diameter, in particular for taking up high axial forces.

Axial securing elements of this type are known (DE-OS 24 50 767). Their development has arisen from the need for an arrangement capable of taking up very high axial forces. This aim was to be achieved by providing obliquely extending contact surfaces instead of using the usual, rectangular securing rings fitted into grooves extending perpendicularly to the engaging surfaces.This modified arrangement was to provide a larger area of contact and a different distribution of forces but it has the disadvantage that the known conical securing rings used in this arrangement have a relatively high resistance to bending and are therefore difficult to force open as well as entailing the risk that they are liable to be forced open too far, especially if the grooves are fairly deep, because the maximum bending moments produced by opening up the rings under these conditions may become so great that the elastic limit of the material used is exceeded.

It is therefore an object of the present invention to provide an axial securing element of the type defined above which is capable of taking up large axial forces without providing any difficulties in assembly and without the stress limit of the axial securing elements being exceeded under deformation on account of their cross sectional form.

In an axial securing element of the type mentioned above, this problem is solved by providing the ring elements in the form of at least two part elements which can be assembled independently of each other but cooperate with each other. Although this formation entails at least one additional operation in assembly, it provides the great advantage that since the spreading process results in a smaller change in the radii of curvature of the axial securing elements so that the bending moments to be applied are smaller and/or the axial securing elements have in any case a smaller resistance to bending, the forces to be exerted during assembly and dismantling are relatively small compared with those required in the known arrangements but the axial force capable of being taken up in the assembled state is greater than has hitherto been possible.The invention is also based on the knowledge that the magnitude of axial forces which can be transmitted depends not on the surface area of contact with the parts to be secured but only on the depth of the groove, which in turn determines the cross-section and hence the moment of resistance of the securing element employed. The invention enables a great depth of groove to be obtained in the assembled state without the disadvantages of the known forms of construction of restricting the capacity of the elements to be opened up or the forces which are to be applied for this purpose.

Subdivision of the ring elements into partelements may be achieved by various means. The part elements may advantageously consist of ring segments formed by subdividing a ring at its circumference. Since all the ring segments can only be inserted in their grooves by elastic deformation in much the same way as a securing ring which is split in only one position, they cannot fall out of their groove once they have been inserted between the parts which are to be secured. This formation therefore has the great advantage that the moments of bending and tension produced in the individual ring segments during assembly or dismantling are much smaller and less unevenly distributed than the bending moments and tensions which occur when opening up an otherwise closed ring, at least at the point of the greatest bending moment.The shortest dimension obtainable for a given axial force to be transmitted can be achieved when the part elements are square in cross section and the part elements and grooves are so arranged that the diagonal of the square forming the profile cross section is perpendicular to the engaging surfaces. The grooves or notches then have an angle of 900 at the base and extend into the engaging surface at an angle of 45 0. The smailest moment of resistance against bending for a given depth of groove may thereby be achieved. The depth of the grooves is advantageously chosen so that each of the part elements has only half its cross section held in the groove. The greatest possible depth of groove can then be utilized for transmitting the axial forces.

Alternatively, the ring may be subdivided into part elements consisting of ring parts having differing means diameters, with the internal and external contours, respectively, of adjacent ring parts so adjusted to each other that the parts fit together along the surfaces facing each other.

Thus whereas in the first embodiment the rings, which normally only have single splits, are subdivided into segments, in this embodiment the rings are subdivided concentrically around the circumference. These ring parts may have a rectangular cross section in profile, each with half the cross section of a square, and two ring parts may lie in contact along one side of each in such a manner that the end faces of the rectangles are in alignment. The two ring parts, which are separate, independent parts, thus combine to form a ring of square cross section. Since they can be assembled and dismantled separately, the bending moments and tensions produced are again considerably less than those which would be produced in a ring made of only one part.

These ring parts may be fitted differently to the one or other of the parts to be secured, depending upon whether assembly and dismantling is achieved by spreading the ring parts outwards and then letting them snap back into the groove with an increase in their curvature or whether the ring parts are assembled or dismantled by pressing them together and subsequently letting them spring back into a groove which is open to the inside.

It is also advantageous if the grooves have only one surface of contact, preferably extending at an angle of 450 to the engaging surfaces and preferably designed for the insertion of securing elements of square cross section, and one depression situated opposite to this surface of contact and ending in a rounded portion which is continuous with the engaging surface. This design has the advantage that the notch effects produced by the groove can be reduced without the risk of impairing the effectiveness of the groove. The ring elements may, of course, be subdivided into individual ring segments as well as being subdivided into concentric rings or ring parts of differing diameters; the maximum bending moments and tensions occurring may thereby be even further reduced.

It is further advantageous if one or more of the part elements which together are square in cross section engages in only one of the two grooves associated with each work piece and if the two squares composed of one or more part elements lie in contact with each other along a lateral surface. The securing elements thereby obtained have overall a rectangular cross section formed by fitting together two part elements each with square cross section. This arrangement has the great advantage that, for example, a shaft can be secured axially in both directions against a hub or the like but the axial securing device is inserted only at one location and can easily be fitted into place. Such bilateral securing has not been possible with the securing rings hitherto known.

Further features and advantages of the invention will be apparent from preferred embodiments described below by way of example and illustrated in the drawings, in which Fig. 1 is a schematic representation of the axial securing of a shaft end against a hub or the like, Fig. 2 is a schematic top plan view of the axial securing element according to the invention used in Figs. 1 and 4, composed of three individual ring segments designed to be inserted in the outer groove, Fig. 3 is a section through the securing element of Fig. 2 taken on the line Ill-Ill, Fig. 4 shows another type of axial securing in which the axial securing element is inserted in a groove on a shaft, Fig. 5 illustrates the example of axial securing of a ball bearing both on a shaft and in a bore, Fig. 6 is an enlarged view of detail VI of Fig. 5, Fig. 7 shows a means of axial securing similar to Fig. 1 but using an axial securing element consisting of two split ring parts lying concentrically one against the other, Fig. 8 illustrates a form of axial securing similar to that of Fig. 4 but again using two ring parts lying concentrically together, Fig. 9 shows an axial securing arrangement similar to that of Fig. 7 but with ring parts of rectangular cross section lying with their lateral surfaces against those surfaces of the bore and shaft which take up the axial forces, Fig. 10 shows an axial securing arrangement similar to that of Fig. 8 but in this case it is the end faces and not the lateral surfaces of the ring parts which make contact with the surfaces transmitting the axial forces, and Fig. 11 shows how a shaft may be axially secured in a bore in both directions by means of two ring parts of square cross section placed in contact with each other and inserted, one in a notch in the shaft and the other in the bore, the left half of this figure showing the notch with the surface of contact for both rings in the bore while in the right half of the figure this notch is provided on the shaft.

Fig. 1 shows the end of a shaft 1 axially secured in a housing or a hub 2 by means of an axial securing element 3 according to the invention. In the example illustrated, this axial securing element 3 consists, as shown in Figs. 2 and 3, of three ring segments 3a, 3b and 3c each extending over an angle of about 1200 and manufactured from curved wire having a square cross section. Axial securing is achieved by inserting these ring segments into a groove in the form of a notch 4 cut out of the hub 2.This notch is triangular in cross section with an angle of 900 at the base and is positioned so that its two lateral walls meet the cylindrical engaging surfaces 5 of the shaft 1 or hub 2 at an angle of 450. The depth t of the notch 4 is chosen so that up to half of the cross section of the axial securing element 3 or of the ring segments 3a, 3b and 3c is received in the notch 4 while the other half extends into the bore 6 in the hub 2. The upper lateral surface of the axial securing element 3 then fits against a 450 slope 1 a of the shaft 1 so that the shaft 1 is axially secured against any displacement in the direction of arrow 7.With this design, the axial forces exerted on the hub 2 by the shaft 1 are taken up by the normal forces directed perpendicularly to the lateral surface 3' of the axial securing element 3 or perpendicularly to the lateral surfaces 4' of the notch 4.

The same applies to the axial securing arrangement of Fig. 4 which differs from that of Fig. 1 only in that the axial securing element 3, which otherwise has the same form as shown in Figs. 2 and 3, is inserted in a notch 8 of shaft 1 and secured against axial forces acting in the direction of arrow 9 by a surface with a 450 slope 2a on the hub 2.

The embodiments shown in Figs. 1 and 4 differ in the manner in which the axial securing element 3 is inserted. In Fig. 1, each individual ring segment 3a, 3b and 3c is gripped at its ends by a tool which slightly presses it together before it is inserted in the notch 4 where it springs back into its original form so that it lies without tension inside the notch 4 and cannot fall out since it is positively fitted into the notch. Alternatively, each ring segment 3a, 3b and 3c may be placed with one end against the notch 4 on its outer surface and then progressively pushed into the notch along its circumference. In the simplest case, this is done by hammer and punch.

If the shaft 1 is to be axially secured in both direction while it is still longitudinally displaceable, an axial securing element 3 may be placed radially into a notch 4 by hand and the shaft 1 may then be pushed with its 450 siopAng surface 1 a against the inserted securing element 3 until it is positively fitted to it. The second securing element is then placed into position by tool as described above.

In the example illustrated in Fig. 4, the individual ring segments 3a, 3b, 3c must be inserted by first spreading them apart since the axial securing element 3 is to be inserted obliquely into the notch 8 of shaft 1 from outside, and the segments then snap back into the notch so that they are freed from tension and positively engage in the notch so that they cannot be dislodged by an oblique forward displacement.

In Fig. 5, two axial securing elements 3 of the type according to the invention are provided both on the internal diameter and on the external diameter of a ball bearing 10 to secure both the external ring and the internal ring of the ball bearing 10 in the axial direction, in one case against the part 20 and in the other against the shaft 1.

Fig. 6 shows that the groove 4 need not necessarily be in the form of a notch with a 900 angle at the base as illustrated in Figs. 1 and 4. In order to reduce the notch effect to a minimum, the groove may, as shown in Fig. 6, comprise only on one side thereof a side wall 4' extending at an angle of 450 into the cylindrical engaging surface 5, while on the other side, starting from its deepest point, the groove forms a depression 12 of varying size and shape which continues into a rounded portion 11 ending in the engaging surface 5. Here again, the axial forces are transmitted through the two diametrically opposite contact surfaces 3' and 3" of the axial securing element 3 which is square in cross section.One side 3" of this securing element bears against the contact surface 4' while the side 3' bears against the internal ring 1 Oa of the ball bearing 10 which lies with its rounded edge against the axial securing element 3.

Figs. 7 to 10 illustrate another embodiment of the axial securing arrangement according to the invention. In this case, the axial securing elements 3 consist of at least 2 ring parts 3d and 3e which are split open at one point in the usual manner.

These two ring parts have different diameters but are so formed that they make complete surface contact along the sides 13 and 14 facing each other. Furthermore, the ring parts 3e and 3d are designed so that their end faces 1 5 and 1 6 are in alignment so that together the two parts form an axial securing element 3 which is square in cross section. This element is inserted in the groove 4 and bears against a 450 slope on the shaft 1. In the example of Fig. 7, the end faces 15 and 16 are positioned so that they bear against the side walls which take up the forces on the groove 4 and on the sloping surface 1 a. To place these rings into position, the ring part 3e is first pressed together and then pushed obliquely into the conical space between the groove 4 and shaft 1 while it is being released.The ring 3d is then inserted in a similar manner. To remove the ring parts, the operation is reversed The ring parts 3e and 3d may, of course, be inserted in the groove 4 one after the other before the shaft 1 has taken up the position illustrated, and the shaft may then be placed in position. In the Example of Fig. 9, which shows the same arrangement for axially securing a shaft 1 in a hub 2, ring 3e is again inserted before ring 3d. The ring parts 3e and 3d are in this case arranged so that it is not their end faces 1 5 and 1 6 but their lateral surfaces which bear against the wall surfaces which transmit the forces.

Figs. 8 and 10 show analogous embodiments for securing a shaft 1 in a hub 2 against forces acting in the direction of the arrows 1 7. The difference here is that the ring parts 3d and 3e are inserted in the groove 8 of the shaft 1. For this purpose, they are not compressed before assembly as in the embodiments of Figs. 7 and 9 but spread open and pushed over the shaft 1. This embodiment also provides the advantage that by virtue of the ring being subdivided into two halves, namely the ring parts 3d and 3e, the forces required for compressing it or spreading it open are relatively small even if the grooves 4 are deep and the axial securing elements 3 employed therefore have a relatively large square cross section. In this case, the elements may again be assembled or dismantled when the shaft 1 has already taken up its end position in relation to the hub, as already mentioned above.The ring parts 3d and 3e as also the ring segments 3a, 3b, 3c may be pushed open or pressed together in known manner by providing apertures or eyes at the ends of these parts or steps or chamfered ends for the application of a suitable tool as sometimes also used for known types of securing rings and spring rings.

Fig. 11 shows another type of axial securing arrangement which differs in that the end of the shaft 1 is axially secured in its hub 2 or similar housing both in the direction of arrow 7 and in the direction of arrow 1 7. This is achieved by providing a groove 4 in hub 2 and a groove 8 in shaft 1, as shown in the left half of Fig. 11, and inserting in groove 8 a ring part 3f of square cross section which bears against another ring part 3g, also square in cross section, which is inserted in a groove 4 in hub 2. To assemble these securing elements, ring part 3f is first opened up to be inserted in groove 8 with shaft 1 either removed or in position, shaft 1 is then placed in position if not already there, and ring part 3g is then pressed together to be inserted obliquely from outside into the remaining annular recess between the ring part 3f and the groove 4.It is clear that the rings 3f and 3g may again have radii greater or smaller than those of their associated grooves so that a bias tension may be produced. One advantage of this arrangement is that axial securing can be achieved in both directions by the insertion of securing rings in only one position. This may be important, for example, when in contrast to the embodiment of Fig. 5, the shaft and/or the hub 2 is accessible only from one side. In the embodiment shown in the left half of Fig. 1 , the two side walls of groove 4 are not equal in size, one side wall 4"' being twice the size of the other to accommodate both ring parts 3g and 3f. The side walls of the groove 4 are again set at right angles to each other and extend at an angle a of 450 into the cylindrical engaging surface 5.

Axial securing in both direction is also achieved in the embodiment shown on the right hand side of Fig. 11 although in this case the external groove 4 in hub 2 has the form of an isosceles, right angled triangle in cross section while groove 8 has one side wall 8"' twice the size of the other.

To assemble the securing element in this case, the ring part 3g is first compressed to be inserted into groove 4, and it is at the latest at this stage that shaft 1 is placed in position by bringing the surface 8"' into contact with this ring 3g, and the ring parts 3f are then opened up and subsequently drawn together to be inserted into groove 8 so that the parts are secured in the axial direction.

In all the embodiments illustrated in Figs. 7 to 11, the ring parts 3d, 3e, 3f and 3f could, of course, also be subdivided into ring segments in the circumferential direction, thus combining the advantages of a subdivision in the circumferential direction with those obtained by a sub-division in the radial direction.

Claims

1. Axial securing element for fixing together two work pieces having internal and external cylindrical engaging surfaces, respectively, consisting of split ring elements of rectangular cross section which have conical external surfaces set obliquely at an angle of less than 90" to the engaging surfaces and can be inserted in notches on the work pieces by a change in their diameter, in particular for taking up high axial forces, characterised in that the ring elements (3) are composed of at least two part elements (3a to 39) which can be placed into position independently of each other but cooperate with each other.

2. Axial securing element according to Claim 1, characterised in that the part-elements consist of ring segments (3a, 3b, 3c) formed by subdividing a ring (3) at its circumference.

3. Axial securing element according to Claim 1 or Claim 2, characterised in that the partelements (3a, 3b, 3c, 3f, 3g) have a square profile in cross section.

4. Axial securing element according to Claims 1 and 3, characterised in that the part elements (3a, 3b 3c, 3f, 3g) and the notches (4) are so arranged that the diagonal of the square forming the profile cross section is perpendicular to the engaging surfaces (5).

5. Axial securing element according to Claim 4, characterised in that the depth (t) of the notches (4) is so chosen that each of the part elements (3a, 3b, 3c, 3f, 3g) is held in the notch (4) by only half its cross section.

6. Axial securing element according to Claim 1, characterised in that the part elements consist of split part rings (3d, 3e) of differing mean diameters and with their internal and external contours so adjusted to each other that the part rings fit into each other with their surfaces facing each other.

7. Axial securing element according to Claim 6, characterised in that the part rings (3d, 3e) have a rectangular cross section in profile, each rectangle being half a square, and two sides of adjacent part rings lie in contact with each other in such a manner that the end faces (1 5, 1 6) of the rectangles are in alignment.

8. Axial securing element according to Claims 6 and 7, characterised in that the part rings (3d, 3e) lie with the end faces (15, 16) of their profile cross section in contact with those surfaces (4') of the notches (4) which transmit the axial forces and/or in contact with the counter surface (1 å) on the work pieces (1,2).

9. Axial securing element according to Claims 6 and 7, characterised in that the part rings (3d, 3e) lie with their lateral surfaces against the surfaces (4') of the notches (4, 8) transmitting the axial forces and/or against the counter surface (la) on the work pieces (1,2).

10. Axial securing element according to Claim 1 and one or more of the other Claims, characterised in that the notches (4, 8) have only one contact surface (4'), preferably extending at an angle (a) of 450 to the engaging surfaces (5), and, extending opposite thereto, a depression (12) ending n a rounded portion (11) which is continuous with the engaging surface (5).

11. Axial securing element according to one of the Claims 1 to 10, characterised in that each of the two notches (4, 8) associated with each work piece (1,2) receives only one of the part elements (3f, 39) of square cross section and that the two part elements lie with one lateral surface of each in contact with each other (Fig. 11).