DE390391C - Process for the production of tapered rings for roller bearings - Google Patents

Description

The mass production of conical bearing rings for ball bearings and roller bearings took place hitherto regularly by the fact that 'initially by forging or pressing in a die Blanks of the approximate shape of the finished rings, but with excess material, produced and the surfaces, in particular the inner surface, by means of a lathe or milling machine to the necessary exact measure

X _{0 were} worked, whereupon they were hardened by suitable heat treatment, usually case hardening, and then the ready-to-use conical ring was finished by grinding. Aside from the expensive and costly machining, the hardening resulted in so much warping of the ring that a considerable part of the hardened surface was completely abraded by the grinding, so that the rings were unusable for their purpose. In contrast, the X ^ experience according to the invention is characterized in that cylindrical rings or flat disks of uniform wall thickness are driven directly by means of a conical mandrel from the exact outer diameter of the later bearing running surface with an equally conical or less conical die into the final conical shape of the finished ring, whereupon, if you start with discs, after cutting off the bottom and top edge, hardening the running surface and, in exceptional cases, a slight regrinding of the same is sufficient to complete the tapered rings that can be used in the bearing. If cylindrical rings are used as the starting material, the outer diameter is taken to be equal to or slightly larger than the largest outer diameter of the finished conical ring, so that when the ring is driven into the die, the material is not stretched, but rather compressed and compressed. Furthermore, in this case, when the rings are cut from a drawn steel pipe, the inner wall is made precisely cylindrical and smooth by reaming or expanding with a driving mandrel. If flat disks are used as the starting material, these are cut out of sheet metal that has been machined smooth on both sides. .

The advantage of the new process is that it requires a great deal of machining is saved, it should be noted in particular that the exact 'expansion of a Pipe by reamer or drift is much easier than the production conically machined surfaces as well as the plan machining of sheet metal parts. Further falls the grinding work continues almost entirely, and if a slight regrinding is required, so is driven because of the exact concentricity observed after hardening with these It is not possible to grind through the hardened skin and thus render the rings unusable for the intended use fear,. ■. ■. ■

390891

The drawing explains the new process, namely Fig. Ι shows the end view a cylindrical tube which forms the workpiece from which the individual rings are cut to length and finished.

Figure 2 is a side view of this tube, with the dashed lines indicating the ring sections imply.

Figure 3 is a side view of a cut green ring.

Fig.4 is a vertical section of the die with the cut ring in the Starting position and the stamp in the upper position in view. Fig. 5 is a vertical section through Die, punch and pressed ring with the punch in the lowest position.

Fig. 6 shows a finished ring with the same wall thickness,

Fig. 7 a similar one with a greater inclination of the inner surface than that of the outer surface. Fig. 8 to 12 show different stages of production of such a bearing ring, if this is pressed from a flat piece of sheet metal.

Fig. 8 shows the piece of sheet metal, Fig. 9 a cross section through the same after completion of the drawing process,

Fig. 10 shows a section through the partial finished ring after expelling the soil,

Fig. 11 shows the ring with the upper edge dressed while

Fig. 12 shows the ring trimmed with the lower edge.

Up to now, it has been customary to start with a suitable one in the manufacture of conical bearing rings Drill out the workpiece inside and work out the inside surface to the desired size, by means of suitable heat treatment to harden and then finish the work piece by grinding. A common result of heat treatment at this ancient procedure was a warping or throwing of the ring by so much that djjrch a considerable part of the hardened surface was completely sanded off during the grinding process, and in some cases the warping was so severe that it became necessary to discard the ring.

According to the present invention, in one embodiment of the method, a seamless tube A made of drawn steel of cylindrical cross-section is advantageously used. This tube is cut to length in short pieces or rings A ¹ of approximately the same or a slightly smaller length as the finished rings. Both the inner and outer surfaces of the ring are approximately cylindrical and concentric, so that a ring wall of the same thickness is formed throughout. In order to achieve accuracy and concentricity of the inner surface at low cost, it is advantageous to expand the inside of the ring to a diameter which is slightly smaller than the desired one and then finishing it simply by rubbing it out in a press.

At this stage of manufacture, the ring A ¹ forms a cylinder; the next step is to transform this cylinder into a precise conical ring with an inner and an outer concentric surface. This can be done either by expanding or compressing the cylinder, the latter being the case. is preferable. In order to compress the cylinder into a cone, ^{the end of the cylindrical ring yi 1 is} pressed into a strongly tapered die C , the effective inner surface 1 of which forms a hollow cone, the diameter of which is slightly larger than the total diameter of the ring at the head end of the die merges into the total diameter of the finished conical ring at the bottom of the effective die surface, whereby the effective surface is to be understood as the part of the same against which the ring rubs.

Connected to the punch D or in one piece with it is a mandrel 3 which is arranged exactly axially with the die bore and the outer surface of which is a cone, the size and inclination of which corresponds to the inside of the finished ring. When the Ring.'i is inserted into the die ¹ and is set by the punch under pressure, the ring is driven into the die. This process reduces the diameter of the ring by as much as it contacts the inner surface of the die so that the outer surface of the ring becomes equal to the inner surface of the die. At the same time, the inner surface of the ring becomes the same as the outer surface of the dome. A suitable ejector E loosens the ring in the die.

If the surface of the dome has the same slope as the inner surface of the die, the cylindrical ring of uniform wall thickness A ^{1 is converted} into a conical ring A ² of the desired size and shape with the same wall thickness, as Fig. 6 shows. If, on the other hand, the inclination of the mandrel surface deviates from that of the inner die surface, the metal is pressed into the annular space between the mandrel and the die in order to obtain a conical ring A ^s , the inner surface of which corresponds to the inclination of the mandrel and the outer surface of which corresponds to the inclination of the die, such as Fig. 7 shows. In both cases, the ring surfaces are finished with sufficient precision that further processing is not necessary before hardening or coaling takes place. The ring is now ready for the little additional one

Machining, such as bringing to an exact radius or rounding the inner edges, bevelling or otherwise processing the rim to mate with other members of the bearing. These minor edits do not form the subject of the invention.

The next stage in the process is coaling the cone rings in the usual manner

ίο or any other heat treatment for; Purposes of hardening. Since these rings have circular cross-sections and either walls of equal or gradually increasing-! the wall thickness, the tendency to warp is very small, if at all i those on during the heat treatment; occurs. The shape of the ring easily allows small irregularities that occur in the event of a slight throw, to be eliminated:

same. As a result, there is practically no waste in the heat treatment and little or no need to regrind the hardened surface. With others In other words: the grinding that was previously necessary can be omitted entirely. In addition, the Shape of the rings to fit different sizes into each other during heat treatment and thereby results in considerable savings. The possibility of this interlocking is also beneficial for storage and shipping.

The main advantage of collapsing

of the ring instead of an elongation is that this creates a substantial tensile stress which can tear the wall. Upsetting is also suitable better for leveling out unevenness in the wall thickness and makes the metal more granular and more homogeneous.

Although it is advantageous to use a cylindrical tube A as the starting workpiece, the method can also be carried out with a piece of sheet metal or a flat sheet metal strip B as the starting workpiece. Advantageously, the two surfaces of the flat strip are precisely machined. Then the workpiece is cut from the strip, placed in a die and drawn into the shape of a conical cup B ¹ . The bottom of the same _; is then ejected so that the conical ring B ² of Fig. 10 is formed. The top edge! this ring B ^s (Fig. 11) and the lower edge of the conical ring B ¹ (Fig. 12) are then dressed in order to achieve the correct dimension for the finished bearing ring. Then the cone ring is hardened, and if a very precisely machined surface is required, it can still be lightly sanded. Because of the shape of the ring, there is no noticeable warping due to the heat treatment.

Claims (2)

Patent Claims: ι. Process for the production of tapered rings for roller or ball bearings, thereby characterized in that in order to enable the completion of the rings that can be used in the bearing by cold pressing in the die, without any reworking of the running surface other than hardening, edge trimming Cylindrical to the exact height and a slight regrinding in exceptional cases as a workpiece for the die Rings used are cut \ on a cylindrical steel tube that by rubbing out and widening by means of a driving mandrel or the like. Both to the approximately exact largest wall thickness of the finished ring as well as the smoothness of the inner surface that forms the running surface during use, wherein the cylinder from which the workpiece rings are cut is given an outside diameter of is equal to or slightly larger than the largest outside diameter of the finished ring, so that when the ring is driven into the die, the material is only compressed and is compressed, but not stretched, whereupon these cylindrical workpiece rings are rolled into one by a tapered mandrel The die is pressed above the limiting the longitudinal movement of the pressing piece Stop has the exact conical shape of the finished ring, while the conical mandrel has the exact shape of the tapered running surface, followed by hardening and edge cutting after ejection takes place at the exact height. 2. The method according to claim 1, characterized in that ■ in place of one drawn steel pipe as the starting workpiece sheet metal strips from the approximately exact The greatest wall thickness of the finished ring must be used, at least on the surface that will later become the running surface forms, are machined smooth, whereupon round disks are punched out of these strips and Sinks of the same shape as when using the ring workpieces are pressed into the shape of a cup, of which Wall shows the shape of the finished ring and the remaining straight bottom is subsequently cut off. For this 1 sheet of drawings.