JPS5924896B2 - How to roll form bearing rings using cylindrical metal pieces - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for obtaining a bearing ring by rolling a cylindrical metal workpiece.

When rolling forming a workpiece, the workpiece is clamped between two forming members that compress the workpiece into a shape given by the contours of the forming members.

In this way, molded articles with excellent contours can be produced.

However, heretofore, it has not been possible to reliably obtain mutually identical rolled products from a series of rolling steps, since there is no guarantee that the forming member always rolls the work piece in the same position.

Furthermore, in the conventional rolling method, the rolled product does not have a uniform width dimension, and the metal material undergoes thermal distortion due to excessive heating during rolling. This often resulted in negative effects.

The object of the present invention is to eliminate these conventional drawbacks, and to ensure that the workpiece is not subjected to strain, especially in the width direction during rolling, that the required contour is formed in the correct position, and that the workpiece does not lose its circularity. In particular, it is an object of the present invention to provide an improved rolling forming method for a bearing ring in which both side end faces are properly regulated in all rolled products.

The present invention therefore provides a method for properly positioning and rolling forming cylindrical metal workpieces from the outset.

That is, in this method, a cylindrical metal workpiece is placed on a rotatable shaft parallel to the axis of a forming roll having a contour for forming the cylindrical metal workpiece, and one of its inner and outer peripheral surfaces is The work piece is formed by supporting the work piece on the surface and then pressing a forming roll against the other circumferential surface while rotating.

In this case, the forming rolls are provided with diametrically outwardly flared flanges on both sides, which regulate the shape of the ends of the workpiece and also determine the widthwise extent of the workpiece during rolling. .

The inner surface of the flange of this roll is inclined outward at a small angle of less than one angle with respect to a direction perpendicular to the axis of rotation of the roll.

This sloping of the inner surface of the forming roll flange reduces or eliminates scratches and tears on the sides of the work piece.

Also, the slope of the inner surface of these flanges provides better flow of metal.

By using such rolls, it is possible to form the workpiece accurately, and the contour to be given to the workpiece is given at a precise position with respect to the workpiece, so that the workpiece is rolled in this way. The molded products will be equivalent to each other.

If a cylindrical workpiece of known volume is used as the starting material, the lateral flanges of the rolls adjust the widthwise extent of the workpiece during rolling.

That is, after the metal of the workpiece fills the width of the forming rolls, it begins to move up and down the inside sides of the flanges.

Because these flanges are inclined at only a small angle with respect to the direction perpendicular to the axis of rotation of the rolls, the final overall width of the rolled workpiece is determined by the metal migrating diametrically inside the flanges. It only matters to a very small extent compared to the extent to which it does.

The degree of this flow can be adjusted fairly precisely by adjusting the rolling time.

Therefore, the rolled workpiece has a precisely known width and the coined contours are precisely located from both sides of the workpiece.

Therefore, if a further finishing step is to be applied to the rolled workpiece, such as polishing, for example, the position of the rolled workpiece can and should be determined by its side edges. This allows accurate positioning of the rolled contour.

Typically, the shaped workpiece is heat treated and then finally polished to the correct size.

After rolling according to the invention, the workpiece formed during this heat treatment exhibits relatively little distortion.

Also, only a very small amount of material is removed during the polishing step required to provide a precisely finished bearing ring.

In contrast, when a bearing ring is molded by conventional methods, more material is lost during the polishing process than in the present invention.

Additionally, since rolling for forming does not involve the removal of material, there is less loss of raw material compared to mechanical forming methods such as cutting, and therefore the bearing ring is more durable than various conventional methods. According to the method of the invention, it can be manufactured more economically.

The workpiece is first positioned along its axis relative to the forming rolls.

This can be carried out very simply by holding the workpiece elastically between opposed spring parts.

The pressure exerted by these spring elements in this case automatically centers the workpiece in the correct position in relation to the forming rolls and ensures that the widthwise extension of the workpiece is uniform for all workpieces. guaranteed.

The invention is applicable where the workpiece is supported on a rotatable mandrel and is rolled, for example between a pair of forming rolls, to form a profile on the outer circumference of the workpiece, and where the workpiece is typically one piece. It can also be applied to the case where the contour is formed on the inner peripheral surface of the workpiece by rolling with a forming roll and an outer support roll.

All corners of the forming part of the forming roll should have as large a radius as possible to better promote metal flow and also prevent metal entrapment.

It has been found that this also contributes to preventing the formation of cracks in the formed workpiece during subsequent heat treatments.

The flange inner surface of the forming roll should preferably be drawn tangentially from these rounded corners.

For example, a rolling machine for forming the contour of the outer circumferential surface of a workpiece, such as for forming an inner bearing ring, is
It has two movable frames, each with one driven forming roll.

A rotating mandrel is placed between the two frames, onto which the workpiece to be formed is fitted.

The workpiece is rolled between the forming rolls and the rotating mandrel by the rotation of the rolls and the forward movement of the frames facing each other.

During rolling, sometimes the workpiece to be formed breaks.

This generally occurs when the workpiece has low stiffness.

The reason for the fracture is believed to be fatigue of the metal due to distortion of the work piece from circularity during rolling.

As the workpiece rotates during the rolling operation, the circumference of the workpiece tends to increase.

Since the diametrical length measured along the coining force line cannot increase, the diametrical length measured on the 90th power line with respect to the coining force line increases, increasing the flatness of the workpiece. Cause.

This therefore causes the workpiece to vary in diameter between these two lengths.

In this case, the number of times the change in length is reversed depends on the number of revolutions of the forming rolls and the inward feed rate.

This results in the ring-shaped blank being alternately placed in compression and tension, which rapidly causes fatigue failure.

Considering this problem, the method of the invention is therefore carried out by a rolling mill consisting of the following parts:

In other words, these parts include a rotating shaft on which a cylindrical workpiece is mounted during rolling, at least two heads mounted at equal angular intervals around the workpiece, and each head capable of shaping the workpiece into the desired shape. In order to roll the workpiece, a 1-drive forming roll is placed on it so that the forming roll can be moved in the diametrical direction of the workpiece, and the workpiece is centered correctly along its axis relative to the forming roll. A resilient holding device is arranged to maintain contact with the workpiece in the peripheral area of the workpiece between the forming rolls during rolling, and to prevent the workpiece from being substantially deformed from circular shape during rolling. It consists of a pair of rotatable stretch adjustment rolls to avoid excessive metal fatigue.

These elongation control rolls begin contacting the workpiece a little later than the forming rolls and press the workpiece towards the mandrel in the peripheral area of the workpiece between the forming rolls, reducing deformation of the workpiece from circularity; However, at the same time, a pressing force must be applied to the workpiece to an extent that does not actively shape the contour of the circumferential surface of the workpiece.

That is, the elongation adjustment roll simply follows the shaping of the workpiece;
The above-mentioned metal fatigue is also suppressed.

The elongation control roll must be forced against the workpiece during rolling by means of preventing its retreat.

For example, these rolls are propelled by screw feeders or hydraulic rams.

The hydraulic ram prevents the elongation roll from retreating during the rolling process and maintains contact with the workpiece until the desired profile is created.

It has been found that the forces acting on the elongation control rolls reach a maximum value during forming.

For example, if the workpiece is rolled to within about 4 inches outside diameter in a material known as EH11, the maximum force exerted on the workpiece will be about 12,000 pounds.

It may even be desirable for these stretch control rolls to have the same or similar profile to that on the forming rolls and to participate in the forming operation.

In this case, it is desirable that the elongation adjustment roll has the same profile as the modified roll, except that it does not have side flanges.

However, it is used when it consists of a smooth cylindrical elongation adjusting roll.

The elongation adjusting rolls are preferably arranged in opposing pairs or groups of pairs so as not to exert excessive strain on the mandrel supporting the work piece.

The number of elongation control rolls used can vary depending on the size of the work piece and the number of forming rolls used.

If a pair of diametrically opposed heads holds a forming roll, a pair of diametrically opposed elongation adjustment rolls spaced 9σ relative to the forming roll may be used.

The present invention provides a method of rolling a workpiece into a desired shape using a rolling machine as described above.

That is, the workpiece is first placed on the rotatable support shaft by a positioning means having elasticity in the axial direction, and then the forming roll is advanced to start forming the workpiece, and there is also an elongation adjustment roll. In some cases, the workpiece is slightly stamped by rotating forming rolls to set its position.

Thereafter, the workpiece comes into contact with an elongation adjustment roll.

In this case, as already mentioned, the elongation control rolls are sufficient to prevent deformation of the workpiece from roundness between the forming rolls, but with insufficient force to cause substantial shaping of the workpiece. Contact with work piece.

After the work piece has been rolled into the desired shape, the forming rolls and elongation adjustment rolls all begin to retract simultaneously.

In such rolling methods, the initial contact of the forming rolls causes work hardening in the workpiece, so that after the workpiece contacts the forming rolls, the elongation adjustment rolls may distort the forming of the workpiece or may be harmful to the forming. There will be no significant impact.

In order for the stretch adjustment roll to correctly follow the contour formed by the shaping roll, the stretch adjustment roll should be mounted so that it can move elastically in a direction along its axis of rotation.

Once the forming roll reaches a predetermined forming depth, it is desirable to remain in that position for a minimum number of revolutions of the workpiece.

This is because the longer it remains in that position, the greater the diametrical elongation and strain of the workpiece, which causes overheating and breakage of the workpiece.

At the end of the rolling operation, the two sets of rolls begin to retract simultaneously.

If all rolls are pressed against the workpiece by hydraulic rams, the timing of this retraction can be initiated by building up the pressure in the rams that governs the advancement of the head in the opposite direction.

This retraction can be initiated by a timer or by a so-called micro-switch controlled by the position of the ram.

The speed at which the forming roll advances relative to the workpiece is 0.00000000000000 per revolution of the workpiece for workpieces up to approximately 4 inches outside diameter.
Preferably, it is between 0.01 and 0.02 inches.

Typically, rolling mills for forming inner bearing rings have two heads (supporting frames) facing each other in a straight line, which are positioned at diametrically opposite positions of the workpiece during rolling so that the forming rolls are machined. It is desirable to move forward and backward along a path that corresponds to the diameter of the workpiece so as to contact the workpiece.

However, in some cases more than one head may be provided, for example three heads spaced 12σ apart from each other around the workpiece.

Preferably, all heads are driven by hydraulic rams toward the workpiece during the rolling operation.

A similar ram can be fixed to each head, and in this case, by connecting all rams in parallel to a source of water pressure, all heads move equally, thus forming each forming roll against the workpiece and mandrel. Creates a balance in pressure.

A separate mechanical connection may also be provided to advance the head uniformly during the molding operation.

An important advantage of mechanically coupling these heads is that even if there is a small leakage through the seal in these ram cylinders, the mechanical coupling forces movement of the heads, so the piston seals of the hydraulic rams The goal is to make it cheaper and easier to do so.

This method also eliminates the need for multiple replacements of seals.

The present invention is particularly useful for the manufacture of relatively small rings, i.e., inner bearing rings having a maximum outside diameter of 3 to 6 inches.

During rolling, the forming rolls rotate.

This can be achieved with a hydraulic motor driving each forming roll once.

This hydraulic motor has the advantage that the direction of rotation of the rolls can be quickly and easily reversed during rolling when it is sometimes desirable to provide a better rolling surface finish.

In rolling the inner bearing ring, one or more annular recesses are first formed into the outer surface of the cylindrical workpiece.

The inner circumferential surface of the inner bearing ring does not need to be strongly shaped, so the mandrel has a smooth cylindrical surface.

This smooth surface may be formed as part of the mandrel itself or may be the circumferential surface of another cylindrical roll rigidly fixed around part of the length of the mandrel.

The diameter of the forming roll is related to the size of the workpiece, but generally the largest diameter roll specifically used in any given example should be used.

When selecting the diameter of the forming roll, the diameter of the elongation adjustment roll must also be selected.

and chosen as large as possible.

Rolling of the workpiece can be carried out without external heating.

In this case, this rolling is called cold rolling.

Alternatively, rolling can likewise be carried out by preheating the workpiece or by heating it externally during rolling.

In this case, rolling is called hot rolling.

EMBODIMENT OF THE INVENTION Below, the cold rolling mill applied to this invention is described using an Example with reference to an accompanying drawing.

The cold rolling mill 10 shown in FIGS. 1 and 2 consists of a rotatable support, in this embodiment a mandrel 12, and a pair of positively rotating forming rolls 14.

The mandrel 12 is supported at both ends by bearings 16 which are carried by fixed holders 18, whereas the pair of forming rolls 14 are supported by arms 22 of the frame 24.
It is rotatably supported by a bearing 20 inside.

These frames 24 are slidably mounted on a platform 26 and can therefore be moved towards or away from each other.

The holder 18 is fixed to a stand 26.

As shown in FIG. 4, the forming roll 14 has an annular hump 30 at the center of a flat rolled portion 32.
have.

The workpiece 34 is therefore formed in the shape of the inner bearing ring of a ball bearing.

At both ends of the forming roll 14 there are protruding side surfaces (referred to as flanks) 60, the function of which will be described later.

A workpiece 34 is fitted onto the mandrel 12 and supports the smooth cylindrical inner surface of the workpiece during rolling.

Initially, the workpiece 34 slides freely on the mandrel 12, but as the forming rolls 14 compress the workpiece between the rolls and the mandrel, the workpiece is pressed against the mandrel, in which case the mandrel 12 is pressed against the mandrel during the rolling process. It rotates together with the work piece 34.

The frames 24 are mounted to slide on a platform 26, and a hydraulic ram 40 allows the frames 24 to be moved towards each other and away from each other to effect rolling of the workpiece 34.

The two rams 40 are hydraulically connected in parallel as described below.

In this way, the two rolls 14 advance in the same way during rolling and do not subject the mandrel 12 and its bearings 16 to additional stress strain.

As described above, the pair of forming rolls 14 must advance precisely together.

This can be accomplished satisfactorily by making the two rams 40 identical and by hydraulically connecting them in a staggered manner.

In this case, the hydraulic fluid supplied through conduit 124 for advancing the wand 24 is branched to conduits 124a and 124.
24b and uniformly distributed to each ram 40.

Similarly, when retracting frame 24 after a rolling operation, hydraulic fluid is supplied through conduit 126 and communicates to each ram through branch pipes 126a and 126b.

A suitable hydraulic circuit capable of operating ram 40 is shown as part of FIG.

Pressurized water is supplied to supply pipe 152 by pump 150 .

This conduit includes a pressure gauge 154 and a pressure relief valve 1.
55 is installed.

Branch pipe 156 leads from conduit 152 to control valve 158 .

This valve 158 is a branch pipe 124a that moves the ram together.
and 124b and 126a and 126b to control fluid supply and return to conduits 124 and 126 that feed ram 40 in parallel.

Conduit 124 between control valve 158 and ram 40 includes a check valve 16 which controls the speed at which ram 40 can advance forming roll 14 during forming of the work surface and has the functions described below.
A control valve 166 is included which is deactivated by a limit switch 183 to change the forward speed of the ram 40 from high to low.

Switching valve 166 to the right in the illustration bypasses flow control valve 164, and leftward movement of control valve 158 results in the two rams 40 advancing at rapid approximation speeds.

In the preset forward position, a portion of the ram contacts and collapses the limit switch 183.

This de-energizes control valve 166 and allows hydraulic fluid to flow through regulating valve 164, which causes each ram 40 to advance slowly.

Forming roll 14 contacts workpiece 34 at this low speed and remains at this speed until a predetermined rolling depth is reached.

Retraction of forming roll 14 is effected by reversing the action of control valve 158.

This action causes fluid to flow into conduit 126 and branch pipe 12.
6a and 126b before ram 40, and fluid flows after ram 40 to reservoir 61 through check valve 165.

Valve 166 is switched simultaneously with control valve 158.

In order to ensure equal and identical advancement of the two forming rolls 14, the two frames 24 can be mechanically coupled together by suitable means.

The advantages of this mechanical connection have already been mentioned.

The two forming rolls 14 are rotated at the same speed by a hydraulic motor 41 carried by the frame 24.

The advantages of driving the forming roll 14 by the hydraulic motor 41 are as follows:
These are scales whose direction of rotation is rapidly and easily reversed, and which sometimes gives a good finish to the rolled surface.

Next, the means for elastically holding the workpiece on the support in the axial direction will be described.

As shown in FIG. 3, an annular collar 42 is mounted on mandrel 12 on both sides of workpiece 34 and rotates with the mandrel and workpiece.

Each spring 42 is pressed against both sides of the work piece 34 by a pair of springs 44 compressed between the collar 42 and an annular washer 46.

The washer 46 is supported by an annular projection 48 formed on the mandrel 12.

These flanges 42 do not hinder the widthwise extension of the work piece 34, but before rolling is started, the forming roll 1
The workpiece 34 is accurately positioned in the center from the beginning with respect to the annular chevron-shaped protrusion 30 on the top 4, and an appropriate pressing force is applied to the side surface of the workpiece during rolling.

The force exerted by spring 44 can alternatively be exerted by a hydraulic or pneumatic ram acting directly on annular collar 42.

In order to substantially reduce the flattening of the work piece that occurs during rolling, a pair of elongation control rolls 50 are provided facing each other.

These are rotatably attached to a frame 51 via bearings 55, and the frame 51 is further attached to a piston rod 52 of a hydraulic cylinder 53.

The roll 50 includes an annular chevron-shaped protrusion 54 that is the same or similar in shape to the chevron-shaped protrusion 30 of the forming roll 14 .

However, if desired, the elongation control roll 50 may be a smooth cylinder.

As shown in FIG. 2, the pair of hydraulic cylinders 53 are hydraulically connected in parallel to the hydraulic power unit 151 via a switching valve 58.

During rolling, pressurized water is supplied to cylinder 53 through conduit 56.

This causes the piston of the cylinder 53 to advance as the work piece 34 is molded into the desired shape, thereby preventing the piston from retreating.

Therefore, the elongation adjusting roll 50 contacts the workpiece 34 with sufficient force to prevent the workpiece 34 from being significantly distorted.

In this manner, fatigue of the metal is reduced and the likelihood of subsequent fatigue of the workpiece 34 during rolling is reduced.

However, these elongation adjusting rolls 50 do not have a positive shaping effect on the circumferential contour of the workpiece 34.

It simply follows the progress of the shaping by the shaping rolls 14.

However, these rolls 50 maintain the workpiece 34 in contact with the mandrel 12, thus inhibiting workpiece flattening as described above.

An additional flow control valve 200 is installed in the return conduit 57 from cylinder 53 to ensure control of the speed of approach of elongation roll 50 to workpiece 34.

When rolling is complete, valve 58 is switched to the right and operates to supply pressurized water to the rond side of cylinder 53 via conduit 57 and check valve 201.

Pressurized water exiting cylinder 53 returns to reservoir 61 through conduits 56 and 59.

As a result, the elongation adjusting roll 50 retreats from the workpiece 34.

The detailed timing of the recession will be discussed later.

According to one method of the invention, in order to form the cylindrical workpiece 34, the workpiece is first fitted onto the mandrel 12.

For this purpose, the inner diameter of the workpiece is made very slightly larger than the outer diameter of the mandrel, so that the workpiece 34 can easily be attached to the mandrel 12.
You can slide up.

The mandrel 12 holding the workpiece 34 is then reinserted into the machine and the forming rolls 14 rotate.

Furthermore, mandrel 12 and workpiece 34 can be rotated, for example by air or an electric motor (not shown), so that even when workpiece 34 comes into contact with forming roll 14, there is no inherent slippage. It doesn't happen.

Forming rolls 14 are advanced toward each other by hydraulic rams 40 to compress workpiece 34 between rolls 14 and mandrel 12.

The gap between the inner diameter of the workpiece and the mandrel is very small so that once the rolls 14 compress the workpiece, the workpiece 34 and mandrel 12 rotate together.

Since no rolling takes place between the mandrel 12 and the workpiece 34, the inner surface of the workpiece is not shaped and its shape hardly changes.

The rotation speed of the workpiece is governed by the speed of the forming rolls and the relative diameters of the workpiece and forming rolls.

In this case, the rotational speed of the work piece during rolling is 500 rl.
It is 1m.

During rolling, the annular chevrons 30 on the forming rolls 14 form corresponding annular grooves in the outer circumferential surface of the workpiece.

Immediately after forming roll 14 contacts workpiece 34 and initial shaping and surface work hardening occurs, elongation adjustment roll 50 advances into contact with workpiece 34 to reduce to some extent the flattening that occurs in workpiece 34. .

The elongation adjusting roll 50 shown in FIG. 3 has an annular chevron-shaped protrusion 54 corresponding to the forming roll 14.

Therefore, the annular chevron-shaped protrusion 54 on the elongation adjustment roll 50
fits into the groove already formed in the workpiece 34 by the forming roll 14.

To assist with this, it is desirable that the stretch adjustment roll 50 have a certain degree of freedom to move in its axial direction.

Advancement of forming roll 14 continues at a rate of, for example, 0.01 to 0.02 inches per revolution of workpiece 34 until forming roll 14 is completely at the predetermined rolling depth.

Once the full rolling depth is reached, the forming rolls 14 and the stretch control rolls 50 remain in position for a period of time commonly referred to as the "dwell time," i.e., up to two revolutions of the workpiece, after which all rolls are rolled simultaneously. Start retreating.

At the full rolling depth, it is important that the workpiece 34 undergoes a minimum amount of rotation, otherwise overheating and breakage of the workpiece may occur.

Therefore, typically the workpiece 34 should not contact each roll more than about two revolutions after the forming rolls 14 have reached their full rolling depth.

After rolling is complete and forming rolls 14 and stretch rolls 50 have been retracted, mandrel 12 and workpiece 34 are removed from the machine and workpiece 34 is removed from mandrel 12.

The same operation is then repeated using a new cylindrical workpiece.

Preferably, the removal of a formed workpiece and the introduction of a new workpiece are performed automatically in any manner as is done in other operations of the machine.

As described above, the rolling forming method of the present invention is particularly effective in manufacturing bearing rings, and can be performed rapidly with good precision and uniformity.

Furthermore, the provision of the elongation control rolls 50 ensures that metal fatigue and workpiece breakage do not occur during forming of the inner bearing ring.

In addition, in order to form the sides of the workpiece 34, the forming roll 1
4 has a prominent flank 60.

As seen in FIG. 4, the flank 60 is connected to the forming roll 1.
It is not perpendicular to the axis of rotation 63 of 4, but is inclined at an angle α of less than 15° to a line perpendicular to the axis 63.

This has been found to prevent surface damage and tearing at the ends of the work piece which could cause the rolling surface to break and rollback causing damage.

Additionally, it has been found that this slope provides better metal flow.

Furthermore, as shown in FIG. 4, during rolling, the metal flows to fill the contour of the forming roll 14, and the corner 7
0 and further flows to the flank 60.

Here, since the flank 60 is inclined by a small angle with respect to the normal to the rotational axis of the forming roll 14, a change in the metal flow rate in the X direction causes only an extremely small change in the X direction.

Therefore, if the initial shape and size of the workpiece 34 is maintained accurately, the rolled, formed workpiece will have a side surface that includes a point Z that is accurately spaced from the centerline W-W of the formed workpiece. It is possible to produce workpieces which have been shaped in such a way that the contours provided on the workpiece, for example a central groove, are always formed in the exact central position with respect to the side surface containing the point Z.

This is an important advantage if treatments such as polishing are applied to the rolled workpiece after rolling.

In this case, a convenient and accurate positional reference surface is provided at one end of the rolled workpiece.

Generally, the initial workpiece has a different inner and outer diameter and a narrower width than the final finished workpiece.

However, the volume of the workpiece remains constant.

The difference in final size of the formed workpiece depends primarily on the size of the initial workpiece.

Additionally, the workpiece may be chamfered 74 (FIG. 4) before or after rolling.

As shown in FIG. 4, for example, the angle 70
There are no sharp corners to the forming roll 14, as in and 72.

All of these corners have the largest possible radius, and the flanks 60 open tangentially from the corner arcs to the flat portions 32.

In this way, the metal of the workpiece can easily flow in the direction of the arrow El']101, thus reducing stress strains in the forming workpiece.

Additionally, it has been found that this reduces the tendency of the molded workpiece to crack during subsequent heat treatments.

Approximately 13/4 manufactured by the method of the present invention using the above-mentioned rolling machine
The circularity of a typical rolled inner bearing ring with inch hole diameter is shown in FIGS. 5 and 6, respectively, before and after heat treatment.

In this case, the graphs in Figures 5 and 6 were measured at the minimum diameter of the annular groove of the work piece.

Each diametrical scale on the graph represents 0.0025 inch.

Both before and after the heat treatment, the deviation from perfect circularity is relatively small, and it can be considered that almost no distortion occurs during the heat treatment.

This indicates that the ring has an excellent particle flow structure and evenly handles the hoop stress.

Additionally, the very small out-of-roundness and distortion that occurs during heat treatment can reduce the amount of final polishing required to finish the shaped workpiece to its final size.

When molding an inner bearing ring as described above according to the accompanying figures, materials with a surface hardness of 25 to 32 RC give best results, although of course softer materials can also be used.

Figures 7 and 8 illustrate typical cylindrical workpiece sizes before and after rolling in accordance with the present invention, respectively, for forming an inner bearing ring.

The workpiece is made from a material specified by the British Bureau of Standards as EH11 and has a surface hardness of 27RC.

The nominal diameter of the forming roll 14 used was 10 inches,
The "feed" rate of these rolls in forming was 0.01 inch per revolution of the workpiece.

During molding, the rotational speed of the molding roll 14 was 62 rpm.

The maximum rolling force applied by the rolls is 40,000
In pounds, the residence time was 0.75 seconds.

The various sizes of A to ■ in FIGS. 1 and 8 were in inches as shown below.

A...1.5644 B...1.138 C...0.584 D...1.6082 E...-1.1712 F ......0.648 G...0.6397 H...0.6397 ■...1.4523 Next, cold rolling shown in Fig. 9 The machine 80 is, for example, for contouring the inner surface of a cylindrical workpiece 82 to be formed into an outer bearing ring.

The workpiece 82 is rotatably supported by an inner forming roll 84 by means not shown in the figures, and a support which is also rotatably supported by further means not shown in the figures, in this embodiment. Then, it is rolled between outer cylindrical rolls 86.

The inner forming roll 84 has an annular protrusion 88, with smooth cylindrical portions 89 on both sides thereof, and flanks 90 on both left and right sides thereof.

Therefore, the inner forming roll 84 is the above-mentioned forming roll 1.
4 and each equal portion of the inner forming roll 84 performs a similar function.

Therefore, when the workpiece 82 is initially centered with respect to the protrusion 88, the workpiece is accurately formed with side edges similar to the previous example, which side edges are rolled for subsequent operations. It can be used to accurately position the workpiece.

Workpiece 82 is initially centered by resiliently placed collar 92 and tipped hood 94.

The collar 92 is fitted into the outer cylindrical roll 86 and has an annular flange 9 fixed to the roll 86 with bolts 98.
Has 6.

Between the head of bolt 98 and flange 96 is a spring washer 100.

Therefore, collar 92 can be moved in the direction of arrow 102 to compress washer 100.

The top-shaped hood 94 is fitted within the outer cylindrical roll 86, and a rond 104 extending outward from one end thereof is connected to a pneumatic cylinder (not shown) via a not-shown thrust bearing.

The workpiece 82 is first installed into the outer cylindrical roll 86 by sliding it into position against the collar 92.

In this case, workpiece 82 has an outer diameter slightly smaller than the inner diameter of roll 86.

The collar 92 and work piece 82 are then pushed toward the left by the hood 94, as shown in FIG.

In this case, a predetermined pressure is applied to the pneumatic cylinder sufficient to compress the spring washer 100 in order to bring the workpiece 82 into the exact desired position.

Since the washer 100 and the pneumatic cylinder have some elasticity, they do not prevent the widthwise expansion of the workpiece 82 during rolling.

The inner forming roll 84 rotates at 500 rpm, for example.

However, the exact speed of rotation depends on the roll speed and the relative diameters of the various parts, as noted above.

Furthermore, the outer cylindrical roll 86 is pre-rotated so that when the workpiece 82 contacts the forming roll 84, there is essentially no slippage between the two.

Next, the work piece 82 is compressed and shaped by arrow 10.
6, the forming roll 84 moves relative to the outer cylindrical roll 86.

During rolling, the workpiece expands slightly diametrically and fits tightly within the outer cylindrical roll 86.

This ensures an accurate final outer diameter.

When rolling the outer bearing ring, an elongation control roll is usually not used.

The inner bore of roll 86 widens slightly toward the right exit, as seen in FIG.

This makes it easy to insert and remove the work piece.

Next, embodiments of the present invention will be listed.

(1) The forming roll advances at a speed of 0.01 to 0.02 inches per revolution of the workpiece.
The rolling forming method according to item 1 or 2.

(2) The rolling forming method according to claim 2, wherein the elongation adjusting roll has approximately the same contour as the forming roll on its outer peripheral surface and is rotated so as to correctly face the outer peripheral surface of the work piece.

[Brief explanation of the drawing]

Figure 1 is a plan view of a cold rolling mill for rolling a contour on the outer circumferential surface of a cylindrical workpiece, and Figure 2 is an additional illustration of the horizontal circuit used to operate this machine. 3 is a cross-sectional view taken along line 3--3 of FIG. 2; FIG. 4 is an enlarged view of the forming roll of the machine shown in FIG. 1 and a cross-sectional view of the formed workpiece; , FIGS. 5 and 6 are charts showing the diameter deviation of a typical rolled workpiece made on the machine shown in FIG. 1 before and after heat treatment, respectively; FIG. FIG. 8 is an axial sectional view of the workpiece after it has been formed according to the present invention; FIG. FIG. 10... Cold rolling mill, 12... Support mandrel, 14°84... Forming roll, 34,82...
...Processed piece, 44 ...Spring, 50
. . . Elongation adjustment roll, 86 . . . Outer cylindrical roll (support body), 100 . . . Spring.

Claims (1)

[Scope of Claims] 1. A cylindrical metal workpiece is fitted into a rotatable support on its inner or outer circumferential surface, is elastically held and positioned from both sides in the axial direction, and is positioned on this support. On the peripheral surface of the metal workpiece on the side that is not fitted, there is an annular inner surface that extends outward with an inclination of less than one angle with respect to the plane perpendicular to the axis, with chamfered corners on both sides of the outer peripheral surface, and an annular protrusion in between. A suitable number of forming rolls having a diameter of 100 mm are pressed forward while rotating to roll and form a predetermined annular contour on the outer or inner circumferential surface of the work piece, and at the same time, a predetermined annular contour is formed on both sides of the work piece in a manner corresponding to the inner surface. to form an annular side end surface that regulates the spread of the workpiece in the width direction equally on both sides, and when the forming roll advances to a predetermined rolling depth, its advancement is stopped, and the workpiece continues to rotate approximately two more times. A method of rolling forming a ring of a bearing using a cylindrical metal workpiece, characterized by starting the retraction of forming rolls in time. 2. Fit a cylindrical metal work piece into a rotatable support on its inner peripheral surface and position it by elastically holding it in the axial direction from both sides, and position the metal work piece on the side that is not fitted to the support. A pair of forming rolls each having an annular inner surface extending outward with an inclination of less than 1 degree with respect to a plane perpendicular to the axis through chamfered corners on both sides of the outer circumferential surface, and having an annular protrusion between them. After pressing each other while rotating and advancing in a straight line, a pair of elongation adjustment rolls are applied to the outer circumferential surface of the workpiece in a straight line perpendicular to the advancing direction of the forming rolls with a force lower than the pressing force of the forming rolls. While maintaining the roundness of the workpiece, a predetermined annular contour is formed on the outer peripheral surface of the workpiece by rolling, and the workpiece is expanded in the axial direction on both sides of the workpiece in accordance with the inner surface. When the forming roll advances to a predetermined rolling depth, the advancing of the forming roll and elongation adjusting roll is simultaneously stopped, and then the workpiece continues to rotate approximately two more times. A method of rolling forming a ring of a bearing using a cylindrical metal workpiece, characterized by starting the retraction of all rolls at once in time.