DE1236305A1 - - Google Patents

Description

GERMAN # Ä PATENT OFFICE

EDITORIAL

German class: 49-16

Number: 1236 305

File number: R 33827 I b / 49 i

1! 236 305 filing date: November 6, 1962

Opened on: March 9, 1967

The invention relates to a method and a pressing tool for producing metal cages for Needle roller bearings to the effect that the end sections of the cage webs guide the bearing roller bodies in parallel Achieve each other and the rolling elements are held in the radial direction in the cage.

In contrast to conventional roller bearings, in which the bearing rolling elements due to their limited Length-to-diameter ratio are essentially "self-controlling", needle roller bearings require precision-made bearings Cages that are able to hold the rolling elements in their associated axial planes to lead precisely, d. H. in planes that contain the main axis of the bearing. An imperfect one Parallel positioning of the rolling elements in a needle bearing initially leads to a loss of the transmitted Force (reduced mechanical effectiveness) and further to breakage of the rolling elements. The invention relates to hence a method for shaping those protruding into the punched-out rolling body recesses End faces on the slightly inclined circumferential projections of the webs of needle bearing cages Presses in which the end sections of the cage bars are used to guide the rolling elements in parallel and a center piece widened in the circumferential direction on each web and on both sides of it to the end sections the recesses to projections extending in the circumferential direction with protruding End surfaces are provided for the rolling element holder, the middle piece of the web and the end surfaces of the projections in the radial direction with respect to the pitch circle of the rolling elements in opposite directions Sides of the circle are offset.

In cages of this type, each roller body is thus in the circumferential direction through the opposite one another End sections of that pair of webs stored and guided, which rests on the roller body, for this purpose, these opposite end sections of a web of the web pair with the corresponding end sections of the other web a pair of plane-parallel support surfaces for form the roller body, which lie on a common chord plane, the two of which form the roller body between enclosing chordal planes parallel and symmetrical to one another with respect to are the geometric axis of the cage and have a distance between them which is equal the diameter of the rolling element (with the exception of the required fit tolerance). This Cage design is known.

Since the mentioned projections on said opposite end portions of the web ge method and press tool for manufacturing
of end faces on Nadellaa;

Applicant:

RIV Officine di Villar Perosa Societä per Azioni, Turin (Italy)

Representative:

Dr.-Ing. H. Fincke, Dipl.-Ing. H. Bohr
and Dipl.-Ing. S. Staeger, patent attorneys,
Munich 5, Müllerstr. 31

Named as inventor:

Giacomo Einaudi, Turin (Italy)

Claimed priority:

Italy of November 7, 1961 (20 200)

are put and there continue to be the protruding end surfaces of the projections in a conventional manner are formed by rolling or pressing the projections, said support surfaces are necessarily influenced by rolling or pressing, and they are in the finished cage in uncontrollable Way deformed. The subsequent insertion of the rolling elements by snapping them into their associated gaps between the webs is difficult or impossible, and the rolling body are caused to tilt when the bearing is in use.

In contrast, the invention aims at a new and particularly expedient approach to training of the circumferential projections mentioned or their protruding end faces without any adverse effect the longitudinal support surfaces on the webs.

So far, the protruding end surfaces or circumferential projections by exerting a radial Deformation pressure formed on the relevant projection. This radial deformation pressure can be produced by pressing or rolling. Both in one case (pressing) and in the other Case (rollers), the end faces mentioned have a belly, the exact shape and position of which in the Practice are extremely difficult to check, so that on the one hand the end faces often in an undesirable manner are deformed and on the other hand the rolling elements

709 518/147

Difficult to insert into the corresponding window. However, each rolling element must be proportionate Easily snap into its window without causing the two bars to constantly flex. The fact that the needle roller bearings are very small in the vast majority of cases must also be taken into account Have dimensions, the radial thickness of the cage rarely exceeding 2 to 2.5 mm. This explains the difficulties associated with effectively testing a plastic deformation process. It is well known that punching is used to achieve the greatest possible precision must come, but this is practically impossible in the case of needle cages. Since now the deformation pressure a considerable volume of metal to form said protruding end surfaces must displace the relevant projections, the emergence of the above-mentioned bellies cannot be avoided. Practically one tried to counteract the formation of these bellies or theirs Reduce training by having the protruding end faces only after the insertion of the Molds rolling bodies into their respective windows. In this way, every roller acts as an "anvil", at which an excessive flow of metal comes to a standstill during the formation of the end faces. On the one hand But one runs the risk of "choking" the roller body in its window; on the other hand will be the machinery necessary for the production of the bearing is more complicated, since it depends on the technical and from an economical point of view it is more advantageous to first complete the cage and then insert the rolling elements.

The method of the invention is based on three basic requirements:

a) the deformation pressure should be exerted in such a way that it only has a small radial component having,

b) the effective component must extend parallel to the cage axis, and

c) the zone on which the deformation pressure is exerted must be as small as possible (more punctiform or linear contact), so that the highest possible specific deformation pressure is in this zone is achieved even if the total pressure is only relatively low.

In order to achieve the intended purpose under these conditions, the aforementioned method in such a way that the end faces by simultaneous, on both sides of the same Projections exerted, predominantly axially parallel pressure are pressed out.

Characterize advantageous embodiments of pressing tools for performing this method once in that the pressing surfaces are arranged on separately moving pressing tools are or that the pressing surfaces are arranged as a roof-shaped recess on a pressing tool, wherein, according to a particular feature of the invention, said pressing surfaces are concave.

The invention is explained below with reference to exemplary embodiments and schematic drawings explained.

F i g. 1 shows a cross section through a cage blank and a corresponding profile of a cutting machine Machining tool;

F i g. Fig. 2 shows a partial perspective view of the blank of Fig. 1;

F i g. 3 shows a diagrammatic partial view of a projection on a cage web together with one Pair of crimping tools;

Fig. 4 is a view similar to that shown in Fig. 3 with concave pinch surfaces;

F i g. Figure 5 is a partial perspective view of a one-piece simultaneous crimping tool the protrusions on opposite end portions of a ridge;

Figure 6 is a partial cross-sectional view taken along line VI-VI of Figure 6. 5, which is a practical Shows the possibility of achieving concave pinch surfaces on the one-piece tool;

F i g. Figures 7 and 8 show partial cross-sectional views through a protrusion and a tool in two different stages of the squeezing process;

9 and 10 show partial cross-sectional views along the lines IX-IX and X-X of FIG 7 and 8, respectively;

Fig. 11 is a partial axial cross-section view showing a one-piece tool in Working position on a web of the in the F i g. 1 and 2 shows the blank shown;

F i g. 12 shows the view of a cross section along the line XII-XII of FIG. 7;

Fig. 13 shows the partial view of a finished cage which has a rolling body between a Has web pair inserts;

F i g. FIG. 14 shows a view of a cross section along the line XIV-XIV of FIG.

To carry out the method of the invention, a cage blank is required which has a circumferential direction directed projection on each end portion of each web. The kind of Manufacture of such a blank is not essential provided that the tendon support surfaces for the rolling bodies are precisely limited at the opposite end portions of the webs.

Which is experimentally developed as the best method for producing such a blank from turning the inner and outer surfaces of a metal sleeve into a desired profile including a circumferentially continuous projection on each end portion of the sleeve and the subsequent punching of the latter by means of a punch press tool in order in the circumferential direction a number of openings to obtain very precise dimensions for the rolling elements.

In this way, the in Figs. 1 and 2 shown blank 20 opposite end crowns 21 and 22, connected to it, located in the axial direction webs 23 which delimit openings 24 for the rolling elements 25 between them. In the example given, the inner surface of the blank 20 is cylindrical with a constant diameter, while the outer surface is produced on a lathe by means of a single, profiled cutting tool 26 . In this way, the outer surface of the workpiece is simultaneously shaped into a precise profile which has an axial center piece 27 which is situated on a diameter which is smaller than the major diameter of the blank, or which, better said, in the radial direction with respect to on the pitch circle 28 (see Fig. 14) the rolling body is set back towards the inside of said circle. The blank profile also includes a circumferential projection 30 on each end portion 29

each web 23, the summit line or summit surface of the projection 30 being substantially flush with the cylindrical surface. The cross-sectional shape of the projections 30 shown is slightly trapezoidal due to the manufacturing conditions (successful penetration and easy retraction of the cutting tool 26). The flanks 30a of each projection 30 (FIG. 12) are therefore inclined at an angle β relative to a plane 31 perpendicular to the cage axis, the angle β expediently not exceeding 10 °. The cross-sectional shape of the protrusion can also be rectangular, if desired, or it can have a rectangular base followed by a trapezoidal top. Trapezoidal shape also has the effect that a certain deforming pressure exerted on the upper part of the projection produces a lower, non-deforming pressure at the base of the projection, corresponding to the ratio of the respective areas.

The punching process carried out in the radial direction produces openings 24, which are alternately parallel have longitudinal wall surfaces and parallel end wall surfaces. The latter are in the Drawing designated by 32, while each of the longitudinal wall surfaces is a stepped surface represents, soft a pair of plane-parallel end portions 33 and a central part 34, which over the Projecting plane of the end sections 33 in the direction of the opposite, longitudinal wall surface. The inside width of the openings 24 at their end sections is essentially the same as that Diameter of the rolling body 25, as previously determined, while the opposite Surfaces 34 of the middle pieces 27 in each opening are separated from one another by an opening, which is smaller than the diameter of the rolling body. Therefore, the surfaces form the end portions 33 the aforementioned tendon support surfaces for guiding the rolling bodies on a precise, self through the axis of the cage extending plane, and form the widened center pieces of the webs radial inner supports for the rolling elements. Of course, the align due to the punching process opposite end surfaces of each protrusion 30 with their corresponding chordal surfaces 33 so that the ends of the projections 30 do not protrude into the openings 24.

According to the in F i g. 3, in which a web 23 is indicated with one of its projections 30, the upper zone of the projection lies between a pair of pressing tools 36, 37 which are arranged against one another for pressing in the axial direction. The pressing surfaces 36 a, 37 a of the tools are flat and form a kind of "roof" above the projection, since they are so inclined towards one another that they initially only touch the upper edges 30 a, 30 b of the projection 30. Thus, when the tools are axially pressed together, an extremely high pressure is exerted on the upper zone of the projection, the pressure having a limited radial component directed towards the base of the projection. If such a component is distributed over the cross-sectional area of the base, it is insignificant and incapable of producing a permanent deformation, while on the other hand the upper zone of the projection is continued by the high specific pressures exerted on it.

is squeezed while walking. A radially outward flow of metal is caused by said radial component of the pressure is prevented to a sufficient extent so that the metal in the main thing circumferentially in opposite directions along the gap between flows through the tools so as to form protruding end surfaces on the protrusion. There, how through easily ascertained by those skilled in the art, a protrusion of a protrusion end of no more than 0.2 mm into the opening is sufficient to hold a rolling element 3 mm in diameter, the plastic flow of the metal is relatively limited compared to the volume of the protrusion.

The flow of the metal resulting from a central zone of the protrusion length is beneficial relatively little to the formation of the protruding end surfaces; therefore, according to a preferred In carrying out the invention, the squeezing pressure is mainly exerted on the end zones of the protrusion. For this purpose, the in F i g. 4 tools 136 and 137 shown against each other and against the projection 30 has a concave surface 136 a or 137 a. In this embodiment, the four corners 30 'of the projection first touched by the pressing surfaces and plastically to form horn-like projections deformed which extend circumferentially in opposite directions as it will be explained in the following.

Since the tools 36, 37 and 136, 137 press the projection between them, such tools be designed as the two jaws of a forceps-like device. Such a device however, it would be relatively voluminous and sensitive. It has now been shown that the pressing surfaces do not necessarily have to be movable against one another. According to the most advantageous, in Fig. 5 embodiment of the invention shown, a type of embossing tool 40 is used, which has an elongated, flat surface 41, in which transverse grooves 42 and 43 at a mutual distance are formed, which is the same as that of the two projections 30 on a web of the cage to be manufactured is. Each of the above-mentioned grooves has a V-shaped cross-sectional shape and is easily made manufactured by means of a rotating grinding or milling tool, which is shown in FIG. 6 denoted schematically with 44 is. Its cutting surface, the shape of which is double-conical, becomes perpendicular to the surface 41 directed. Tools of this type are often used to make V-shaped grooves when their Cutting surface is directed parallel to the surface to be machined. The diameter of the grinding or Milling tool is smaller than the outer diameter of the cage, so that the curvature of the bottom 45 each of the grooves 42, 43 is greater than the curvature of the ridge 46 of the projection 30 (see Fig. 9). on in this way, according to the double-conical shape of the grinding or milling tool, Flanks 47 and 48 of each groove, which are concave with respect to the projection (Fig. 5).

During the working process, the cage blank 20 (Fig. 11) is attached to a suitable mandrel 50, in each case a web 23 is firmly supported by the mandrel in the radial direction, and the tool 40 in brought up in the radial direction so that it rests on the two projections 30 with its grooves 42 and 43 the web 23 meets. The deforming axial pressure

Claims (4)

is first exerted on the four corners 30 'of the projection 30 through the groove flanks 47 and 48 (FIG. 7), as in FIG. 4 shown. As soon as the tool hits, the protrusion 30 wedges into the groove with the opposite end zones of the protrusion beginning to plastically deform and the protrusion metal plastically flowing circumferentially in opposite directions (Figures 8 and 10). A backflow of the metal is prevented on the one hand by the limited radial component of the occurring pressure and on the other hand by the contact between the projection and the tool, which progressively advances towards the central zone of the projection length. As a result, the projection is squeezed in the axial direction and protruding end surfaces are formed on the projection, which take the shape of horn-like projections 51. Excellent results are achieved with half opening angles α of the wedges of the grooves 42, 43 (FIG. 12), which move between 10 and 35 °. Larger angles up to 40 to 45 ° can also be used, provided that the cooperating tool and projection surfaces are sufficiently lubricated to reduce friction. In addition, the angles α and β should advantageously be approximated in order to obtain a positive differential angle γ in the range of 4 to 5 °, so that a high specific pressure is kept as far away as possible from the base of the projection and thus also from the tendon support surfaces 33 is. 13 and 14 show a general view of the projections 30 on a finished cage with a rolling element 25 snap-fitted between a pair of the webs 23. It can be seen that the horn-like projections 51, which extend from the projections 30 in the circumferential direction in opposite directions, effectively prevent the rolling element 25 from escaping to the outside, the tendon support surfaces 33 remaining undamaged. Compared to the securing projections produced by known methods, the horn-like ends of the present projections have a specific ability in that they are easily rounded by a small amount when an evasive resistance occurs when inserting a rolling element by snapping between them, so that an occasional permanent deformation the ridges when assembling the bearing is avoided. Patent claims: 1. Method for shaping the protruding into the punched roller body recesses End faces on the slightly inclined circumferential projections of the webs of needle bearing cages by pressing, in which the end sections of the cage bars for parallel guidance of the rolling elements serve and a center piece widened in the circumferential direction on each web and on both sides of it, to the end sections of the recesses, with projections extending in the circumferential direction protruding end surfaces are provided for the rolling element holder, the middle piece of the web and the end faces of the projections in the radial direction with respect to the pitch circle of the Rolling bodies are offset on opposite sides of the circle, characterized in that that the end faces (30) by simultaneous, on both inclined sides of the same Protrusion exerted, not covering the entire surface, predominantly axially parallel pressure be squeezed out. 2. Press tool for performing the method according to claim 1, characterized in that that the pressing surfaces (36 a, 37 a) are arranged on separately moving pressing tools. 3. Press tool for performing the method according to claim 1, characterized in that that the pressing surfaces (47, 48) as a roof-shaped recess (42) on a pressing tool (40) are arranged. 4. Press tool according to claim 2 or 3, characterized in that the pressing surfaces (136 a, 137a or 47, 48) are concave. Considered publications:
German Patent No. 1066 530;
German interpretation document No. 1001550. For this purpose 2 sheets of drawings 709 518/147 2.67 ® Bundesdruckerei Berlin